A Study of the Accuracy and Reliability of Sex Estimation

Home , Ischiopubic ramus

A STUDY OF THE ACCURACY AND RELIABILITY OF SEX

ESTIMATION METHODS OF THE HUMAN PELVIS

______

A Thesis

Presented

to the Faculty of

California State University, Chico

______

In Partial Fulfillment

of the Requirements for the Degree

Master of Arts

Anthropology

______

Brenna Kay Blanchard

Spring 2010 A STUDY OF THE ACCURACY AND RELIABILITY OF SEX

ESTIMATION METHODS OF THE HUMAN PELVIS

A Thesis

Brenna Kay Blanchard

Spring 2010

APPROVED BY THE INTERIM DEAN OF THE SCHOOL OF GRADUATE, INTERNATIONAL, AND INTERDISCIPLINARY STUDIES:

______Mark J. Morlock, Ph.D.

APPROVED BY THE GRADUATE ADVISORY COMMITTEE:

______Eric J. Bartelink, Ph.D., Chair

______Beth S. Shook, Ph.D. DEDICATION

To my mom, for all of the sacrifices she made to help me get this far and for always believing in me.

————

In loving memory of my grandpa, Michael Joseph Nugent.

iii ACKNOWLEDGMENTS

The completion of my thesis would not have been possible without the help of my committee, Dr. Eric Bartelink and Dr. Beth Shook. Their insights and guidance have been invaluable. I truly appreciate all of the time they put into reading drafts of chapters and offering helpful comments and suggestions, even while juggling very busy schedules.

I would also like to thank Kristin Chelotti, as the interobserver error portion of this thesis could not have been completed without her help. When she discovered that I needed someone to collect data to compare with my own, she generously offered her time and energy while working and writing her own thesis. Thanks to Shannon Clinkinbeard for access to the CSU-Chico Human Identification Lab, and David Philhour for his help running kappa tests with SPSS.

Thank you to the Anthropology Department of California State University,

Chico. I am grateful to have experienced the rigorous and rewarding educational benefits of being a graduate student in this department. The decision to become part of this department has been one of the best decisions in my life.

Thanks are also due to Dr. Lee Meadows Jantz and Rebecca Wilson for access to the William M. Bass Donated Skeletal Collection, and to the Anthropology

Department at the University of Tennessee, Knoxville. I am also thankful to Guest

Housing at UTK, for providing a safe place to stay on campus for the duration of my data collection in an unfamiliar city.

iv I am also grateful to my cohort of graduate students for all of the love, friendship, and support we have shared over the last four years. I am so happy to call these individuals my friends, and each of them has contributed something significant to my life. I know that these friendships will be a part of my life for many years to come.

Of course I also want to thank my husband, Lance Blanchard, for all of the love and support. In addition to being a fellow graduate student, he is also my best friend, emotional support, sounding board, and the tireless cheerleader who believes I can (and will) do anything I put my mind to.

I must also thank the 227 individuals in my sample who donated their remains

(or were donated by others) to further our scientific knowledge.

v TABLE OF CONTENTS

PAGE

Dedication...... iii

Acknowledgments ...... iv

List of Tables...... viii

List of Figures...... ix

Abstract...... xii

CHAPTER

I. Introduction...... 1

Hypotheses ...... 2 Outline of Thesis ...... 3

II. Literature Review...... 6

Sex Estimation...... 6 Metric Methods of Sex Estimation...... 9 Morphological Methods of Sex Estimation...... 20 The Current Research...... 26 Conclusion...... 27

III. Materials and Methods ...... 28

Source and Demography of Materials...... 28 Methods ...... 30 Statistics...... 39

IV. Observer Error Results ...... 46

Introduction ...... 46 Intraobserver Error ...... 47

vi CHAPTER PAGE

Interobserver Error ...... 52 Summary and Conclusions...... 56

V. Method Results...... 59

Introduction ...... 59 Results ...... 60 Summary and Conclusions...... 102

VI. Discussion...... 104

Introduction ...... 104 Reliability ...... 105 Accuracy...... 110 The Revised Bruzek Method...... 114 Legal Significance...... 117 Summary and Conclusions...... 118

VII. Conclusions ...... 121

Summary...... 121 Limitations...... 126 Implications ...... 126 Conclusions ...... 127

Literature Cited...... 129

Appendices

A. Data: Standards for Data Collection...... 138 B. Data: Bruzek...... 149 C. Data: Maximum Diameter of the Acetabulum ...... 163

vii LIST OF TABLES

TABLE PAGE

1. Intraobserver Error Results...... 48

2. Interobserver Error Results...... 53

3. Results for Morphological Methods ...... 61

4. Percentages of Correct Classifications and Misclassifications for Females Using Morphological Methods...... 62

5. Percentages of Correct Classifications and Misclassifications for Males Using Non-Metric Methods ...... 63

6. Results for the Revised Bruzek Method ...... 96

7. Results for the Acetabulum Method ...... 100

viii LIST OF FIGURES

FIGURE PAGE

1. Greater Sciatic Notch Scoring Criteria from Standards for Data Collection from Human Skeletal Remains ...... 31

2. Ventral Arc, Subpubic Concavity, and Ischiopubic Ramus Ridge Scoring Criteria from Standards for Data Collection from Human Skeletal Remains ...... 32

3. Preauricular Sulcus Scoring Criteria from Standards for Data Collection from Human Skeletal Remains ...... 33

4. Male Preauricular Area...... 34

5. Female Preauricular Area...... 35

6. Male Greater Sciatic Notch...... 36

7. Female Greater Sciatic Notch...... 37

8. Male Composite Arch...... 38

9. Female Composite Arch ...... 39

10. Male Inferior Pelvis ...... 40

11. Female Inferior Pelvis...... 41

12. Male Ischiopubic Proportions...... 42

13. Female Ischiopubic Proportions...... 43

14. Maximum Diameter of the Acetabulum...... 44

15. Ventral Arc...... 64

16. Subpubic Concavity...... 65

ix FIGURE PAGE

17. Ischiopubic Ramus Ridge...... 66

18. Greater Sciatic Notch...... 67

19. Preauricular Sulcus ...... 69

20. Sex Estimations Using the Standards for Data Collection (Buikstra and Ubelaker, 1994) Methods ...... 71

21. Preauricular Area: Negative Relief ...... 72

22. Preauricular Area: Border Type...... 73

23. Preauricular Area: Piriform Tubercle ...... 75

24. Preauricular Area Overall ...... 76

25. Greater Sciatic Notch: Proportion...... 78

26. Greater Sciatic Notch: Symmetry...... 79

27. Greater Sciatic Notch: Contour...... 80

28. Greater Sciatic Notch Overall...... 81

29. Composite Arch...... 83

30. Inferior Pelvis: External Eversion...... 85

31. Inferior Pelvis: Morphology...... 86

32. Inferior Pelvis: Robusticity...... 87

33. Inferior Pelvis Overall...... 89

34. Ischiopubic Proportions...... 90

35. Sex estimations Using the Bruzek (2002) Method ...... 92

36. Sex estimations Using the Sacroiliac Pelvic Complex of the Bruzek (2002) Method ...... 93 x FIGURE PAGE

37. Sex Estimations Using the Ischiopubic Pelvic Complex of the Bruzek (2002) Method...... 95

38. Sex Estimations Using the Seven Best Bruzek (2002) Criteria...... 97

39. Sex Estimations Using the Revised Bruzek Method ...... 98

40. Maximum Diameter of the Left Acetabulum. Sectioning Point = 55.51 mm...... 101

41. Maximum Diameter of the Right Acetabulum. Sectioning Point = 55.62 mm...... 102

xi ABSTRACT

A STUDY OF THE ACCURACY AND RELIABILITY OF SEX

ESTIMATION METHODS OF THE HUMAN PELVIS

Brenna Kay Blanchard

Master of Arts in Anthropology

California State University, Chico

Spring 2010

Sex determination is an important first step in the development of a biological profile in human osteology, as methods to estimate other components of the profile depend on sex. The pelvis is the most sexually dimorphic anatomical region due to obstetrical requirements. This thesis tests sex estimation methods for the pelvis from three sources to determine rates of reliability and accuracy. The sex estimation methods recommended in Buikstra and Ubelaker, the Bruzek method, and the Murphy method were evaluated using remains curated at the California State University – Chico Human Iden- tification Laboratory and the William M. Bass Donated Skeletal Collection at the Uni- versity of Tennessee, Knoxville.

Intra- and interobserver error studies were performed to test reliability between two observations by the author and between the author and a second observer.

xii Intra-rater reliability was high for most traits and combinations of traits. The opposite was the case for inter-rater reliability. Concordance was assessed using Cohen’s kappa and paired t-tests.

All traits, combinations of traits, and sex determinations for the Buikstra and

Ubelaker and Bruzek methods were statistically significant when compared with biological sex. The Murphy method was statistically significant between the sexes. The morphological methods were evaluated using Pearson’s Chi-square and the Murphy method was assessed using independent samples t-tests. The Bruzek method categorized a high percentage of individuals as indeterminate. A revised version of the Bruzek method was proposed, tested, and resulted in a high correct classification rate and low error rate.

A movement toward standardization is occurring in the forensic sciences, which includes finding error rates for identification methods. Validation studies are important for the future of the forensic sciences and the process of standardization because they establish the accuracy, reliability and error rates of previously published methods.

xiii

CHAPTER I

INTRODUCTION

Determination of sex is an important first step in the development of the biological profile in human osteology, whether analyzing a forensic case or an archaeological population. Without an accurate determination of sex, we cannot accurately estimate age at death, as rates of growth, development, and degeneration vary by sex as well as population. Further, stature is estimated with different regression formulae for males and females.

There are many sex estimation methods that can be applied to human remains.

Methods vary from visual assessments to metric analyses of sexually dimorphic traits.

Methods also vary in the elements used; many bones of the human skeleton have been analyzed to assess the degree of sexual dimorphism and accuracy in sex estimation. Some elements have proven to be more accurate than others.

It is important that we know the reliability and accuracy rates of sex estimation methods in human skeletal remains. Forensic anthropologists must use methods that are as accurate and reliable as possible in order to correctly identify unknown individuals. In the case of archaeological populations, it is important that sex estimations be accurate in order to provide the best possible understanding of population demography.

1 2

Validation studies are necessary in order to determine rates of accuracy and reliability, not only for sex determination methods, but for all methods used for human identification. These studies are conducted through replication of previous studies and comparison with reported error rates. Without validation studies it is impossible to know whether a method will perform well beyond the sample it is tested on, or if the results of a published study can be reproduced.

Hypotheses

This thesis examines the rates of accuracy and reliability for sex estimation methods for the pelvis, which are addressed in two major hypotheses. The first pertains to the relationship between biological sex and the methods under investigation. There are morphological differences between the male and female pelvis due to variation in size as well as different reproductive requirements. Since these differences exist, the first hypothesis is that each aspect of the methods, as well as the combination of the aspects and sex determinations made with the methods, will have a significant relationship with biological sex.

If there is a relationship between biological sex and the individual criterion or combinations of criteria for these methods, then there is a greater possibility that the methods will estimate sex reliably and accurately. The second hypothesis relates to the performance of each method in terms of reliability and accuracy. The methods recommended in Standards for Data Collection from Human Skeletal Remains (Buikstra and Ubelaker, 1994) are generally considered both reliable and accurate. The Bruzek

(2002) and acetabulum (Murphy, 2000) methods were published very recently and have

3 not been thoroughly evaluated. One study (Listi and Bassett, 2006) tested the Bruzek method and found that accuracy rates were lower than indicated in the original study.

Until now, the acetabulum method has only been tested with an archaeological sample and has not been validated with a modern sample. The second hypothesis is that there is a difference between these methods in terms of performance.

A relationship between biological sex and sex determinations made using these methods will indicate that the methods utilize sexually dimorphic traits. High rates of both reliability and accuracy for the Bruzek and acetabulum methods will indicate that these methods should be implemented for use in forensic cases, since it is necessary to use methods that can provide accurate and reliable sex estimations. Further, it is important that we continue to test and re-evaluate methods in order to find methods which will provide the most accurate biological profiles for both forensic cases and archaeological populations.

Outline of Thesis

While there are many methods for estimation of sex in the literature, this study focuses on methods based on the pelvis from three sources. The methods recommended for the pelvis in Standards for Data Collection (Buikstra and Ubelaker, 1994) were tested because these methods are considered reliable and accurate, and they have been used successfully for many years. The Bruzek (2002) method was also tested because it incorporates many aspects of the pelvis, claims to have a high accuracy rate, and some of the traits utilized are already known to have a strong relationship with sex. Finally, the maximum diameter of the acetabulum (Murphy, 2000) was tested because it corresponds

4 closely to the femoral head measurement already used as a sex indicator and it lacks validation through research with modern skeletal remains.

Chapter II discusses the sex estimation literature. Methods are divided by the type of data used to make estimations as well as the bone or bones utilized. Metric methods involve taking measurements of skeletal remains and using discriminant functions in order to make sex estimations. Morphological methods involve visual inspection of skeletal remains and assessing the presence, absence, or degree of expression for particular traits. A survey of both types of methods is provided for sexually dimorphic areas of the skeleton.

The skeletal collections at the University of Tennessee, Knoxville, and

California State University, Chico, were used for this research. The demographics of these samples are discussed in Chapter III. The sex estimation methods for the pelvis recommended in Standards for Data Collection (Buikstra and Ubelaker, 1994), the method presented by Bruzek (2002), and the acetabulum method (Murphy, 2000) are discussed in detail in Chapter III. Each aspect of these methods is described, along with scoring criteria, as well as the procedure for measuring the maximum diameter of the acetabulum. Finally, the statistical tests performed to assess accuracy and reliability for the methods are discussed.

It is important to understand how consistently a method performs when used multiple times by the same observer or by multiple observers. An intraobserver error study was conducted in order to determine how well the author’s first and second observations agreed with one another. The interobserver error study was conducted to

5 assess the consistency of determinations made by two different observers. Chapter IV provides the results of both the intra- and interobserver error studies.

Since it is important for methods to be accurate as well as reliable, each criterion was compared with biological sex, as well as the determinations made when criteria were combined. Acetabulum measurements were also tested to determine whether or not they differed between the sexes. The results of all the methods, as well as correct classification and misclassification rates, are presented in Chapter V. An alternative method utilizing the criteria outlined in the Bruzek method is also proposed in this chapter, along with the result of the statistical test performed with it and the correct classification and misclassification rates.

Since this research is important for the practice of physical anthropology in the legal system, some discussion of legal significance is necessary. Chapter VI summarizes the results presented in the two previous chapters and discusses the legal significance of validation studies such as this one. The revised Bruzek method is also discussed further in this chapter.

Finally, Chapter VII summarizes the previous chapters and offers conclusions and suggestions for future research. Limitations of this study and implications for future research are also discussed.

CHAPTER II

LITERATURE REVIEW

Sex Estimation

Determination of sex is an integral first step in the development of the biological profile in human osteology. Sex determination is necessary to make age, ancestry, and stature estimations, as the sexes age differently, exhibit some degree of variation in ancestry-related morphology, and generally differ in height (Stewart, 1979).

Nearly every region and element of the skeleton has been used to develop methods for sex estimation with varying degrees of success. The general anatomical regions used for sex determination are the pelvic girdle, the skull, and long bones, although other bones have also been utilized.

The pelvic girdle is the most accurate area from which to determine sex and methods using these elements tend to make successful predictions in 90 to 95 percent of individuals (Krogman and Işcan, 1986). Sexual dimorphism in this area is mainly due to the changes that occur during adolescence to meet the requirements of childbirth in females (Singh and Potturi, 1978; Işcan and Derrick, 1984; Budinoff and Tague, 1990;

Tague, 2007). The female pelvis grows more in width than height during adolescence, while the growth of the male pelvis maintains the morphological characteristics of both sexes before adolescence (Coleman, 1969). Thus, a wide pelvic inlet, wide subpubic concavity, and a wide greater sciatic notch are the hallmarks of the female pelvis, while

6 7 the opposite characteristics are found in male pelves. In addition to these traits, many other sex indicators of the pelvis have been tested.

The skull is somewhat less reliable for use in determining sex, ranging between 80 and 90 percent accuracy (Williams and Rogers, 2006). Males are generally more robust and larger than females, and this is no less the case in terms of the skull, although for some populations this can be problematic, as females can also show a high degree of rugosity leading to a seeming overabundance of males in a population (Weiss,

1972; Konigsberg and Hens, 1998; Walrath et al., 2004; Walker, 2008). While sexual dimorphism in the human skull is not as pronounced as in many other primates, there are useful sex indicators, such as the nuchal crest, mastoid process, supra-orbital margin, supra-orbital ridge, and mental eminence, all of which tend to be larger or more robust in males than in females (see Buikstra and Ubelaker, 1994). However, some cranial traits appear to be influenced by ancestry to such a degree that sex differences are more difficult to identify unless ancestry is known (Burris and Harris, 1998).

Long bones have also demonstrated usefulness in sex estimation studies.

Muscle attachments tend to be larger in males than females, and long bones tend to be longer and more robust in males than females. Postcranial osteometrics are more accurate than non-metric traits of the skull. However, because of the variation in the activities performed by each sex, the possibility that some females may develop larger muscle attachments than males, and variation in height within populations, long bone morphology is not always reliable for use in sex determinations.

In addition to the elements discussed above, many other bones have been tested for their usefulness as sex indicators. Because these elements tend to have less

8 direct involvement in reproductive requirements or biomechanics, they are generally less reliable than those previously mentioned. One exception to this may be the glenoid fossa, which articulates with the head of the humerus, and has been shown to be useful as a sex indicator. However, metacarpals, metatarsals, phalanges, and several other elements are less likely to be significantly useful as sex indicators across populations.

Age has an important impact on sex determination. Accurate and reliable methods have not yet been developed for individuals who have not reached skeletal maturity, although many attempts have been made (for examples of subadult sex estimation methods, see Weaver, 1980; Loth and Henneberg, 2001; Rissech and Malgosa,

2005; Franklin et al., 2007; Cardoso and Saunders, 2008; Wilson et al., 2008; Vlak et al.,

2008). All of the methods discussed here are applicable to remains of individuals who have reached skeletal maturity.

Regions of analysis are not the only factors for consideration when attempting to determine sex in an individual skeleton. Methods are also divided by the types of data used to make determinations. Metric methods rely on the general observations that males of a given population tend to be larger in skeletal expression than their female counterparts. This type of method utilizes individual measurements or combinations of measurements to separate the sexes and make a determination based on that separation.

Femoral head diameter is an example of a measurement that is greater in males than females, often enough that it can make an adequate estimation of sex. Morphological methods rely on either the presence or absence of certain traits, or the degree of expression for a certain trait. The presence or absence of a ventral arc or the width of the greater sciatic notch are commonly used to estimate sex. More examples of metric and

9 morphological methods, their rates of success, and strengths and problems with both types of methods will be discussed in detail below.

Metric Methods of Sex Estimation

As stated above, metric methods are based on taking measurements of various dimensions of skeletal material. These methods are more easily repeatable than morphological methods because they rely on standardized osteometric points. In addition, metric methods are more objective than non-metric methods, because osteometric landmarks tend to be easier to find on a consistent basis and their assessment is not based on judgment against a scale of expression. Another strength of metric analysis is that simple measurements can be transformed into indices, thus eliminating the bias in using size itself as a sex indicator (Arsuaga and Carretero, 1994).

Metric Sex Estimation Using the Pelvis

Letterman (1941) measured the maximum width and height of the greater sciatic notch and the distance between the posterior inferior iliac spine and a line drawn from the point of greatest depth of the notch. All three measurements revealed significant differences between males and females. Females had wider notches and larger distances between the posterior inferior iliac spine and point of greatest depth, while males had greater notch height. Greater sciatic notch morphology was also assessed by Singh and

Potturi (1978) with various measurements. Again the distance of a line drawn between the point of greatest depth and the posterior inferior iliac spine proved to be an excellent indicator of sex.

Univariate and multivariate analyses of the Coimbra collection utilizing 34 linear variables revealed that for most innominate dimensions males are larger than females (Arsuaga and Carretero, 1994). However, when shape variables are taken into account, females are larger than males in all variables which possess obstetrical significance. A discriminant function using 14 of the original 34 variables resulted in a predictive rate of 98.6 percent for males and 100 percent for females.

Murphy (2000) used maximum acetabular diameter to determine sex in a sample from New Zealand. A discriminant function was derived using these measurements, which was then used to estimate sex. Since the sample consisted of archaeological remains, a long bone measurement and discriminant function with a reported correct classification rate of 97.6 percent was compared with the acetabular measurement (Murphy, 2000:40). Concordance between the discriminant functions for the acetabulum and the long bones achieved 85.2 percent for left acetabula and 86.2 percent for right acetabula. In a more recent study utilizing the acetabulum (Benazzi et al., 2008), digital photographs were used to take measurements. Correct classification ranged from 94.9 percent of cases for males to 97.7 percent of cases for females.

Geometric morphometric analysis, used to turn morphology into a quantifiable entity, was utilized with 121 innominates from the Coimbra collection (Gonzalez et al.,

2009). Photographs were taken of the greater sciatic notch and the ischiopubic complex, and landmarks were placed along the edges of the images to measure the shapes of these areas. Accurate sex estimations were made in 90.1 to 93.4 percent of cases, indicating that this method and these areas may be useful for sex assessment.

Flander (1978) measured nine dimensions of length and breadth of 200 sacra from the Terry Collection. Discriminant functions derived from the measurements accurately sexed 80 percent of white males, 88 percent of white females, 94 percent of black males, and 88 percent of black females. Further research from Benazzi and colleagues (2009), utilizing the digital photographs of the sacral base, revealed a prediction rate of 92.1 percent in their Bolognese sample and 84.2 percent in their

Sassarese sample (88.3% correct classification for the pooled sample). Inter- and intraobserver error was assessed and no significant differences in measurements were found.

Additionally, unlike the method described by Flander (1978), this method can be used even with an incomplete sacrum, as long as S1 is intact.

Metric Sex Estimation Using the Skull

Norén et al. (2005) measured the lateral angle of the petrous portion of the temporal bone in order to estimate sex. Casts were taken of the auditory canal, which were then measured and sexed based on the findings of Graw and colleagues (2003). The analysis determined that the angles less than 45° were indicative of males, while those greater than 45° were females. Norén et al. (2005) discovered that the lateral angle had a correct classification rate of 77 percent for males and 88.3 percent for females, and correlated more precisely with sex determinations made using pelvic morphology than cranial morphology. Another sex determination method utilizing the petrous portion of the temporal bone is presented in Lynnerup et al. (2006). This method uses the minimum diameter of the internal acoustic meatus as measured by drill bits, which revealed statistically significant sexual dimorphism for both the unilateral and bilateral samples.

The mastoid triangle, an area defined by the area between porion, mastoidale, and asterion, has also been used to estimate sex. Paiva and Segre (2003) determined that the mastoid triangles of males tend to be greater than or equal to 1447.40 mm2, while those of females tend to be less than or equal to 1260.36 mm2. Kemkes and Göbel (2006) were unable to attain values similar to the previous research, although their findings did reveal a significant difference between male and female mastoid triangles. However, this method only achieved a correct classification rate of 65 percent, thus making this method only slightly better than chance.

Gapert and colleagues (2008) analyzed the occipital condyles to estimate sex.

Maximum condyle length and width, maximum bicondylar breadth, the minimum distance between condyles, the maximum interior distance between condyles, and the external hypoglossal canal distance were all measured to develop discriminant functions.

The most predictive measurement was bicondylar breadth, while the measurement with the least predictive value was maximum width. Sexual dimorphism did achieve statistical significance in this archaeological sample, but the authors assert that this method should be tested on a modern sample and may be of use only in the case of fragmentary remains.

Several dimensions of the palate have been tested to estimate sex, although these measurements more often discern differences between individuals of different ancestries than individuals of different sexes (Burris and Harris, 1998). While this method performs better (65-67%) if ancestry is known, correct classification of sex is not high enough to justify its common use for sex estimation.

Metric Sex Estimation Using Long Bones

Black (1978) contends that there are differences between male and female long bone circumferences due to the increased cortical appositional activity which occurs to a greater extent in males during adolescence. Femoral circumferences and lengths from individuals at the Libben site were measured and discriminant functions were developed from the data. The function which utilized femoral length performed better than the circumference function, correctly classifying 89.4 percent of remains compared to 85 percent. In a study analyzing the circumference of all long bones, humeral minimum circumference and circumference at the nutrient foramen of the tibia proved to be the most sexually dimorphic; the rate of success for all long bone measurements ranged from

75.9 to 90 percent (Safont et al., 2000). Another study in which all long bones were utilized, Pomeroy and Zakrzewski (2009) found that the only significant sex difference in diaphyseal shape for the upper limb was found in the right radius in one of their samples.

For the lower limb, males in the Spanish sample exhibited higher mean indices at femoral midshaft and lower mean indices at the tibial nutrient foramen and tibial midshaft, all of which were significant, while males in the British sample only differed significantly in tibial nutrient foramen indices.

Three measurements of the femoral head – supero-inferior diameter, antero- posterior diameter, and circumference – have been utilized for discriminant function analysis with an archaeological sample of Polynesians (Murphy, 2005). Measurements of males were consistently greater than those for females, and accuracy in sex estimation ranged from 80.9 to 82.4 percent when compared with pelvic morphology. Asala (2002) used a combination of six demarking points of the femoral head to assess sex in

14 individuals of South African origin. This research achieved an accuracy rate of 100 percent, although sex was determined in only 47 percent of the femora. At best this method could be used to support an estimation with another method, but only in a case where the measurements fall neatly into the male or female categories.

In a study of Chinese femora measurements, all dimensions were significantly greater in males than females (Işcan and Ding, 1995). Midshaft circumference was the best dimension for determining females and femoral head diameter was more successful in determining males. Six discriminant functions were developed through this research and accuracy ranged from 81.7 to 94.49 percent. King and colleagues (1998) used the same measurements to determine sex in a sample of Thai femora, and again all dimensions were significantly larger in males than in females. The discriminant functions developed with this sample ranged in prediction accuracy from 85.6 to 94.2 percent, with the maximum head diameter and bicondylar breadth function performing best. Maximum head diameter and bicondylar breadth also performed well on their own, with correct classifications of 97.1 and 94.3 percent respectively.

Seidemann and colleagues (1998), Stojanowski and Seidemann (1999), and

Frutos (2003) established the usefulness of minimum supero-inferior femoral neck diameter in sex determination in samples which varied geographically and temporally.

Individuals from the Hamann-Todd collection were utilized in a study revealing that minimum femoral neck diameter is greater among African American males than among

Caucasian and African American females (Seidemann et al., 1998). The measurements of

Caucasian males exceeded those of all three of the other groups and the female samples did not differ from each other. Sex estimation accuracy rates varied from 87 to 92 percent

15 for all samples in this study. Stojanowski and Seidemann (1999) used the same functions developed in the previous study with individuals from the donated collection at the

University of New Mexico. The Caucasian sample achieved a correct classification rate of 83 percent and the African American sample resulted in 97 percent accuracy, while the pooled ancestry function resulted in a successful prediction rate of 85 percent. Frutos

(2003) used a Guatemalan sample and demonstrated that this measurement can vary from population to population. Classification rates were poor for the Guatemalan sample using the discriminant functions developed for the Hamann-Todd and University of Mexico collections, ranging from 4 to 36 percent. However, once a population-specific function was developed, a correct classification rate of 89.5 percent was achieved for the

Guatemalan sample. Sexual dimorphism is not evident, however, in the femoral neck- shaft angle (Anderson and Trinkaus, 1998).

Purkait (2005) used measurements of a triangle on the femur, defined by the most lateral projection of the femoral head, the most medially projecting point of the greater trochanter, and the most posteromedial point of the lesser trochanter, to determine sex. When the sexes were combined, correct classification was 86.4 percent for all three measurements of the triangle. Accuracy for the measurements ranged from 62.5 to 86.4 percent when used singly or in combination. Brown et al. (2007) used Purkait’s Triangle to determine sex in a mixed ancestry sample. There was no significant difference between the ancestral groups represented, but there was a statistically significant difference between triangle measurements of males and females. The distance between the greater trochanter and lesser trochanter points correctly classified sex in 85.5 percent of cases, and with the addition of femoral head diameter classification rose to 90 percent.

Using an archaeological sample, Dittrick and Suchey (1986) measured humeri and femora to determine which measurements are most useful in sex estimation for prehistoric central California populations. Correct classification was based on agreement with the sex assessment made with the pubis. For the Early Horizon, the best humeral dimension was vertical diameter of the head, which had a success rate of 85.7 percent, and the best femoral measurement was physiological length, with a success rate of 85 percent. For the combined Middle and Late Horizon sample, vertical and transverse diameters of the humeral head performed the best (90.3% and 89.1% respectively), while the optimum femoral dimensions were maximum diameter of the head (90.6%) and bicondylar width (89%).

Işcan and colleagues (1998) tested six humeral dimensions from Chinese,

Japanese, and Thai skeletons to establish sex determination standards. For all dimensions, male measurements exceeded female measurements to a significant degree, and regional analysis also revealed significant differences in all dimensions except epicondylar breadth. Correct classification ranged from 87 to 97 percent, with the Chinese sample showing the least amount of sexual dimorphism and the Thai sample exhibiting the most.

A method using the epicondylar breadth of the humerus was presented by Albanese and colleagues (2005). This method had a success rate between 57 and 100 percent, which was skewed greatly by the sample sizes used, varying between five and 109 individuals.

However, the authors argue that by adding epicondylar breadth to the humeral head measurement, and finding a grand mean of the two measurements with a large enough sample, accuracy was between 90 and 100 percent.

Research presented at the American Academy of Forensic Sciences annual meeting by Grant and Jantz (2003) used length of the semilunar and radial notches and width of the proximal rim of the olecranon process. A high degree of sexual dimorphism was found with these dimensions, resulting in a correct classification rate of 93.2 and

95.5 percent for white males and females respectively, while black males and females were assessed correctly in 92.6 and 97.1 percent of cases. In a test of this method, Cowal and Pastor (2008) used the same measurements and added radial notch width and coronoid height. Sex was estimated accurately in 92.3 percent of individuals with the five combined dimensions, and male ulnae were significantly larger in all measurements.

Further research utilizing radial and ulnar maximum lengths revealed that these measurements are consistently greater in males than in females, and the accuracy in determination of sex using these measurements was 96 percent (Celbis and Agritmis,

2006). In a study utilizing radial head diameter, 96 percent of individuals were sexed correctly when both sides were used, 92 percent when only the left was used, and 94 percent when only the right was used (Berrizbeitia, 1989).

Metric Sex Estimation Using Other Elements

Murphy (2002a) examined the pectoral girdle for signs of sexual dimorphism in a Polynesian sample from New Zealand. Measurements were taken of the antero- posterior diameter of the acromial end and maximum diameter of the sternal end of the clavicle in addition to the maximum height and breadth of the glenoid fossa. A discriminant function was developed using these measurements, which resulted in an accuracy rate of 97.7 percent. Murphy used the same sample to assess the usefulness of the tarsals in sex estimation. Male tali were consistently larger than female tali, and

18 accurate sex estimations were made in 85.1 to 93.3 percent of cases (Murphy 2002b). The calcaneus was also consistently larger in males than females, resulting in a correct classification rate of 88.4 to 93.5 percent (Murphy, 2002c). Further research using measurements of the talus and calcaneus in a modern Italian sample of known sex resulted in 87.9 to 95.7 percent correct sex determination (Gualdi-Russo, 2007).

Jit and colleagues (1980) used measurements of the sternum to determine its use as a sex indicator with the remains of a North Indian sample. Accuracy ranged from

29.55 percent for females and 50.32 percent for males for the mesosternum to 62.50 percent for females and 72.12 percent for males for the combined manubrium and mesosternum measurements, indicating that this is not a particularly sexual dimorphic bone in this sample. In a study utilizing the fourth sternal rib end, maximum supero- inferior length and antero-posterior breadth were the most useful for sex determination and were used to develop discriminant functions (Koçak et al., 2003). The sex of the youngest individuals in the study was correctly classified in 88.6 percent of cases and

86.5 percent of the individuals in the older group.

One study utilized 13 dimensions of the hyoid for sex determination in a cadaveric sample (Reesink et al., 1999). While all dimensions were greater in males, only three measurements were significantly larger. Despite the significant differences, the best discriminant function produced through this research achieved a correct classification rate of 76 percent. Kim and co-workers (2006) used weight and 33 other measurements of the hyoid for sex determination. The male hyoid was heavier and larger in 20 of the 33 other measurements than was the female hyoid. Using these dimensions, a discriminant function was developed which successfully predicted sex in 88.5 percent of males and

87.9 percent of females, leading the authors to assert that the hyoid is a useful bone for sex estimation, at least for the Korean population.

Sex determination has also been attempted with the metatarsals, metacarpals, and phalanges. Barrio and colleagues (2006) took eight longitudinal and transverse measurements of the metacarpals and derived discriminant functions from them. Males had significantly larger metacarpals than females, particularly in the transverse dimensions. Case and Ross (2007) used metatarsals, metacarpals, and phalanges of the hands and feet to determine sex. The hands proved to be better predictors of sex, with a correct identification rate of at least 80 percent for all digits (but not the metacarpals), while only the first distal phalanx of the foot came close to achieving an 80 percent success rate. The left hand was especially useful, as two of the discriminant functions based on the left phalanges produced success rates which exceeded 85 percent. In a recent study of sexual dimorphism of the carpals, discriminant functions correctly classified 73.2 to 87.8 percent of the left carpals, while accuracies ranged from 71.7 to

88.6 percent for the right (Sulzmann et al., 2008).

The Terry and Hamann-Todd collections, as well as an archaeological sample, were used to test the first cervical vertebra as a sex indicator (Marino, 1995). Linear regression and discriminant function analyses were performed using eight dimensions of the first cervical vertebra. Individuals from the Terry collection were sexed correctly in

75 to 85 percent of cases, 60 to 77 percent were classified correctly in the Hamann-Todd collection, and the archaeological sample showed concordance with other sex estimation methods in 70 to 85 percent of individuals. Discriminant function analysis was also performed using seven measurements of the patella (Introna et al., 1998). Correct

20 classifications were made in 62.5 to 78.8 percent of cases when only one measurement was used, and accuracy increased with the use of discriminant functions, achieving a successful determination rate of 76.3 to 83.8 percent. The best function utilized the maximum width and thickness of the patella.

Morphological Methods of Sex Estimation

Morphological methods can be more problematic than metric methods, as determinations utilizing visual observations are based on traits with degrees of expression that vary by sex, age, and ancestry, as well as through time. Assessment of these traits can also differ between observers. Determinations made based on the presence or absence of a trait that also has an intermediate form can be tricky as well. However, morphological methods in general do not require the use of tools and can often be made relatively quickly by an anthropologist with many years of experience in the field

(Stewart, 1979). In addition, determinations can be made in some cases where remains are fragmented, which is a problem with metric analyses (Rogers, 1999). Published visual methods are based mainly on the features of the bones of the pelvic girdle and skull, although a few other elements have been utilized.

Morphological Sex Estimation Using the Pelvis

Phenice (1969) reported a method using the pubis, specifically the ventral arc, subpubic concavity, and ischiopubic ramus ridge. Each trait was scored as either present or absent. When a trait was present, this indicated a female, while absence of a trait indicated a male. Phenice achieved a correct classification rate of 96 percent using these characteristics. Lovell (1989) published a validation study of this method, which reported

21 an accuracy rate of 83 percent, though Lovell points out that age may be a factor, as the individuals in this study were older than those in the original study. Phenice’s method has been adopted in Standards for Data Collection (Buikstra and Ubelaker, 1994), with the addition of a score for ambiguous morphology. Buikstra and Ubelaker (1994) also recommend the scoring of the presence of the preauricular sulcus and morphology of the greater sciatic notch.

The presence of a preauricular sulcus has been used to determine sex, although this trait is rarely a reliable indicator on its own. In a study conducted by Dee

(1981), six percent of males and 26 percent of females exhibited a sulcus in the preauricular region. Houghton (1974) identified two different types of preauricular sulcus, one of which is shallow and short and can occur in both males and females, and a sulcus that is deep and wide, occurring only in females. Kelley (1979) and Cox and Scott

(1992) have also published research using the preauricular sulcus, although these studies centered on assessment of parturition status. Since this trait is more often found in females who have given birth, it can be a useful indicator of sex. However, the absence of this trait does not necessarily indicate that an individual is male.

The Arsuaga and Carretero (1994) study discussed in the previous metric methods section also tested ten non-metric variables and found many sex differences in expression of these traits. The highest rate of correct classification achieved in this portion of the study was over 75 percent, utilizing the preauricular sulcus, robusticity of the pubic crest, ventral arc, subpubic concavity, ischiopubic ramus and its junction with the pubic symphysis, and sciatic notch shape. While the morphological variables were

22 more likely to incorrectly classify females, metric variables did not reveal a significantly different tendency to correctly classify either sex.

Buikstra and Ubelaker (1994) recommend a scoring system for the greater sciatic notch which ranges from one, indicating strongly feminine morphology, to five, which indicates strongly masculine morphology. Walker (2005) analyzed this scale and found that rather than indicating feminine morphology, the score of two seems to indicate morphology that is intermediate, as high numbers of both males and females were assigned a score of two. This study also indicated a degree of morphological variation due to population and age.

A method proposed by Bruzek (2002) utilizes 11 features from the preauricular surface, greater sciatic notch, composite arch, inferior pelvis, and ischiopubic proportions. When all five of these areas were assessed together utilizing two

European samples, the combined sample was correctly classified in 95 percent of cases, while one sample achieved a success rate of 98 percent (Bruzek, 2002). In a test of the

Bruzek method, Listi and Bassett (2006) achieved correct classifications in 90 and 92 percent of cases, compared with 95 and 96 percent correct classification using traditional methods. Debono and Mafart (2006) developed an abridged version of the Bruzek method to determine sex in a historic collection from France. The abridged version was meant to be used with fragmentary remains and used the five best performing features: border type, greater sciatic notch proportion, symmetry, and contour, and composite arch.

Concordance with the original study was 92.7 percent.

Research conducted by Patriquin et al. (2003) compared sex determination methods between black and white males and females from South Africa, focusing on

23 pubic bone shape, subpubic concavity, ischiopubic ramus form, orientation of the ischial tuberosity, and greater sciatic notch shape. The best indicator of sex for females was pubic bone shape, which resulted in correct classification for 96 percent of whites and 88 percent of blacks, while the best indicator for males was ischial tuberosity orientation, which resulted in accurate sex determinations in 96 percent of whites and 92 percent of blacks.

In addition to characteristics of innominates, some researchers have developed methods using the sacrum for sex determination. Tague (2007) analyzed the costal processes of S1 to determine the degree of sexual dimorphism present. Males exhibited significantly smaller costal processes of S1 compared to the dimensions of the lumbar vertebrae as well as the dimensions of the female costal processes. Belcastro and colleagues (2008) examined the degree of sacral body fusion in two European samples.

Females in this study tended to show more advanced degrees of fusion than did males, and the most common pattern was females who were completely fused except for S1-2.

Işcan and Derrick (1984) published a sex determination method using the sacroiliac joint, specifically focusing on the iliac tuberosity, the postauricular sulcus, and the postauricular space. Females in their sample, even the adolescents, consistently exhibited a wider postauricular space than did males, while the postauricular sulcus was somewhat more variable. The iliac tuberosity proved to be the most variable trait studied: all males exhibited this trait, while only half of the females expressed the trait. Dar and

Hershkovits (2006) examined sacroiliac joint bridging as it pertains to sex estimation.

The male morphology for sacroiliac bridging differed from the morphology in females

24 when bridging was present. However, for this method to be useful, at least partial bridging has to have occurred.

Morphological Sex Estimation Using the Skull

Konigsberg and Hens (1998) assessed brow prominence, mastoid size, supra- orbital margin sharpness, nuchal crest development, and chin shape in an archaeological sample. Using the logistic regression model, accurate sex estimations were made in 81.16 percent of the combined sex sample, while the cumulative probit model yielded a combined correct classification rate of 83.33 percent. Walker (2008) used the same traits for a study using a sample composed of modern individuals and a sample composed of ancient Native Americans. The mastoid and glabellar areas proved to be the most successful in sex determination, while nuchal crest and supra-orbital margin were the worst. Sex estimations were the most accurate, achieving a rate of 89 percent, when all five traits were used in conjunction. The Native American sample tended toward more robusticity and less sexual dimorphism than the modern sample.

In a test of 21 cranial sex indicators, Williams and Rogers (2006) reported correct classification rates between 24 and 96 percent for females and between 60 and

100 percent for males. When six of the indicators were excluded because of high intraobserver error rates, overall accuracy was 92 percent, while the use of only the six best performing indicators (size and architecture, supraorbital ridge, nasal aperture, zygomatic extension, mastoid size, and gonial angle) produced an accurate sex estimation rate of 94 percent.

Maat and colleagues (1997) tested the 15 morphological criteria of the skull recommended by the Workshop of European Anthropologists (1980) using a medieval churchyard sample of known sex. Each individual was sexed using the pelvic criteria as well as to determine concordance between the regions. Pelvic criteria were concordant with biological sex in nearly all cases. When the complete skull was available, agreement between skull and pelvic determinations was 96.2 percent, and for crania only concordance was 95.7 percent. However, when only the mandible was present, agreement only reached a rate of 69.5 percent.

Loth and Henneberg (1996) tested the predictive value of posterior ramus flexure in determining sex. For the sample of 200 African blacks, most males exhibited flexure of the posterior border of the mandibular ramus at the level of the occlusal surface of the molars. In females, posterior borders were more often straight or exhibited flexure at a point closer to the condyle. This method was tested again on a sample of more diverse ancestry. For the African sample, sex was accurately determined in 99 percent of individuals, while for the combined sample of African individuals and the test group, which was comprised of pathological Africans and individuals from the Smithsonian

Institution, sex was correctly classification in 94.2 percent of cases (with all groups performing with at least 91% success). However, further research using this method has revealed a much lower accuracy (63%) and significantly different rates of correct classification for males and females (Donnelly et al., 1998).

Morphological Sex Estimation Using Other Elements

Rogers (1999) tested five traits of the distal humerus for estimating sex.

Trochlear constriction, trochlear symmetry, olecranon fossa shape and depth, and angle of the medial epicondyle achieved acceptable rates of accuracy in determining sex, while orientation of the medial aspect of the trochlea to the humeral shaft performed poorly.

When all five variables were tested on samples from the University of New Mexico and

University of Tennessee, Knoxville, these features achieved an accuracy of 94 and 91 percent, respectively, as long as olecranon shape and depth were given greater weight for cases that were otherwise indeterminate.

The presence or absence of a rhomboid fossa of the clavicle, as well as expression when present, was used as a sex indicator (Rogers et al., 2000). As there are varying degrees of expression with regard to the rhomboid fossa, each clavicle was assigned a score between zero (no depression) and three (a large, depressed fossa). Only three out of 113 females in the study exhibited fossae, while this trait was present in 72 of

231 males. According to this sex determination method, a fossa on the right clavicle indicates an 81.7 percent probability that the clavicle belonged to a male, and a fossa on the left indicates a 92.2 percent probability of belonging to a male. This trait appears to be of use in sex determination if it is present.

The Current Research

The research conducted here involves sex determination using the innominate, specifically the methods outlined in Buikstra and Ubelaker (1994), Bruzek (2002), and

Murphy (2000). These methods were used to estimate sex and determine levels of

27 accuracy and reliability in samples from the Human Identification Laboratory at

California State University, Chico and the William M. Bass Donated Skeletal Collection at the University of Tennessee, Knoxville. Methods using the innominate were chosen because the pelvis is the anatomical region with the highest success rate for prediction of sex from skeletal remains.

The pelvic criteria described in Standards for Data Collection in Human

Remains (Buikstra and Ubelaker, 1994) utilize the pubis and posterior pelvis for sex estimation. The Bruzek (2002) method uses all areas of the pelvis to make sex determinations. Finally, Murphy (2000) describes the use of the acetabulum for sex estimation. Chapter III will address each method and the scoring criteria in greater detail.

Conclusion

Nearly every bone in the skeleton has been used for sex estimation, and the pelvis tends to offer the most accurate determinations. Methods are divided by metric analysis and morphological or visual analysis. Both types of methods are similar to each other in accuracy of determinations (Rogers, 1999), and each has its own strengths and weaknesses.

While it is important to have a variety of sex estimation methods utilizing different elements of the skeleton at our disposal in the case of fragmentary remains, it is equally important that we utilize the methods that perform with the highest rates of accuracy. Research must continue to test and retest methods in order to assure that the most accurate, reliable, and valid sex determinations will be made by experts.

CHAPTER III

MATERIALS AND METHODS

Source and Demography of Materials

This research involves the estimation of sex from skeletal remains. Methods from three different sources were utilized to assess levels of accuracy and reliability, using the donated collections at the Human Identification Laboratory at California State

University, Chico, and the William M. Bass Donated Skeletal Collection at the

University of Tennessee, Knoxville. The sample from Chico is composed of 27 individuals, while the sample from Tennessee consists of 200 individuals. As there are no acceptable sex estimation methods for immature remains to date (see Weaver, 1980; Loth and Henneberg, 2001; Rissech and Malgosa, 2005; Wilson et al., 2008 for some attempts at determining sex in juveniles), only adult remains were utilized for this research.

The remains curated at the lab at CSU Chico comprise donations and forensic cases. There are 5 males, 5 females, and 17 individuals of unknown sex. Since not all individuals are of known sex, only the individuals for whom this information is available will be included in the comparative analyses. Ages are known for four individuals and range from 38 to 87 years, with a mean age of 71.3 years. The sample consists of nine whites (33.3%) and one black (3.7%). Ancestry is unknown for 17 individuals (63%).

Individuals from the collection at UT Knoxville were donated to the university for the purpose of conducting research. All individuals in this collection were

28 29 donated between 1981 and the present. This research was conducted using the remains of individuals who died between 2003 and 2007. Of 200 individuals, 132 are male (66%) and 68 are female (34%). Ages range from 24 to 99 years, with a mean of 58.2 years.

Variation in ancestry is minimal. Whites make up 90 percent of the sample (180 individuals), 7 percent of the sample is black (14 individuals), 2 percent of the sample is

Hispanic (4 individuals), and 1 percent of the sample is of Native American or Asian descent (one individual each).

The entire collection at UT Knoxville at the time of data collection consisted of 699 individuals: 509 are males (72.8%) and 190 are females (27.2%). Ages range from

16 to 101 years, with a mean age of 59.9 years. Variation in ancestry is similar to the smaller sample taken from the collection for this research. Whites make up 89.7 percent of the sample (627 individuals), 7.9 percent of the sample is black (55 individuals), 1.9 percent of the sample is Hispanic (13 individuals), 0.3 percent of the sample is Native

American (two individuals), and 0.1 percent of the sample is Asian (one individual). One individual is of unknown ancestry.

The individuals selected for this research were chosen with the intention of getting a representative sample. Individuals were selected from the most recent donated remains available, a group which contains a higher percentage of females than the earlier donations (34% versus 23.8% females in the unutilized portion of the sample available at the time of data collection). Estimations of sex were made for each individual without prior knowledge of biological sex.

Methods

Three sources were used to estimate sex in each sample. Both the left and right innominates were assessed when available. The CSU Chico data was collected in

May and early June of 2009, and the UT Knoxville data was collected between June 29 and July 6, 2009. Data was collected a second time for the CSU Chico sample in

September 2009 in order to conduct an intraobserver error study. A second researcher

(another M.A. student) also collected data independently from the CSU Chico collection so that an interobserver error study could be completed.

Methods from Standards for Data Collection

The methods described for sex determination in Buikstra and Ubelaker (1994) were used. The greater sciatic notch, ventral arc, subpubic concavity, ischiopubic ramus ridge, and preauricular sulcus have been used in thousands of forensic cases as well as in the assessment of many archaeological populations. Scoring of the greater sciatic notch was completed according to the directions given in Standards, holding the notch six inches above the diagram to determine which shape best fits each individual (Figure 1). A number between one and five was assigned to each notch for each individual, corresponding to sex as follows:

1. female morphology

2. probable female morphology

3. ambiguous

4. probable male morphology

5. male morphology

Fig. 1. Greater sciatic notch scoring criteria from Standards for Data Collection from Human Skeletal Remains.

Source: Buikstra JE, Ubelaker D. 1994. Standards for data collection from human skeletal remains: Proceedings of a seminar at the field museum of natural history. Fayetteville: Arkansas Archeological Survey Research Series No. 44. Reprinted with permission.

The ventral arc was scored as present, thus female, if a clear arc was found, while the lack of an arc was scored as absent (Figure 2). A ridge that is present but does not follow the typical female morphology was scored as ambiguous. The subpubic concavity was scored as present, absent, or ambiguous. A narrow, ridged ischiopubic ramus was scored present (female) and a broad, flat ischiopubic ramus was scored as absent (male), while morphology between these categories was scored as ambiguous.

The last sex indicator for the innominate found in Standards is a scale for the assessment of the preauricular sulcus (Figure 3), which is found more often in females than males (Dee, 1981; Buikstra and Ubelaker, 1994). This trait is scored from zero to four, based on the degree of expression:

0. absence of a preauricular sulcus

1. wide, deep sulcus

2. wide, shallow sulcus

Fig. 2. Ventral arc, subpubic concavity, and ischiopubic ramus ridge scoring criteria from Standards for Data Collection from Human Skeletal Remains.

Fig. 3. Preauricular sulcus scoring criteria from Standards for Data Collection from Human Skeletal Remains.

3. narrow, deep sulcus

4. narrow, shallow, and smooth-walled sulcus

After sex scoring was complete for each individual using the methods in

Buikstra and Ubelaker (1994), the same individuals were assessed a second time using the method described in Bruzek (2002), which utilizes several dimensions of the pelvis.

The preauricular surface, greater sciatic notch, composite arch, inferior pelvis, and ischiopubic proportions are scored as having male, female, or indeterminate morphology.

Bruzek Method: Preauricular Surface

The preauricular surface area comprises three separate criteria used by Bruzek

(2002). The presence of a paraglenoid groove along the antero-inferior edge of the auricular surface indicates a male, as does a piriform tubercle, found at the location of the posterior inferior iliac spine, due to the relationship between these traits and muscular

34 activity. Absence of a groove or sulcus in the preauricular area also indicates a male

(Figure 4). The presence of a preauricular sulcus indicates a female (Figure 5). Since both

Fig. 4. Male preauricular area.

a paraglenoid groove and a preauricular sulcus will be located in the same area, differentiation of these traits is necessary. If a depression is located in the preauricular area the groove border is scored as either open (paraglenoid groove) or closed

(preauricular sulcus). Only those preauricular areas which score as one sex on all three criteria will be considered true sex identifications, while those which have any combination of male, female, and indeterminate scores will be considered less reliable identifications.

Fig. 5. Female preauricular area.

Bruzek Method: Greater Sciatic Notch

For the Bruzek sex estimation method using the greater sciatic notch, proportion, symmetry, and contour are assessed. A line is drawn between the posterior inferior iliac spine and the ischial spine, and another line is drawn from the deepest part of the notch, intersecting with the first line. Other lines are then added so that two boxes have been drawn (Figures 6 and 7). If the two segments formed by the lines are of equal proportions, this criterion is scored as female, while disproportionate segments lead to the scoring of a male. If the notch is relatively symmetrical, it is scored as female, and an asymmetrical notch is scored as male. The last greater sciatic notch criterion, contour of the posterior segment, is scored as female if the posterior contour is enclosed within the drawn box. However, if the contour of the posterior segment extends beyond the drawn box, this criterion is scored as male.

Fig. 6. Male greater sciatic notch.

Bruzek Method: Composite Arch

The composite arch used by Bruzek is identified by examination of the anterior edge of the auricular surface and the anterior chord of the greater sciatic notch. If the curves form a single arch, the composite arch is scored as absent and is indicative of male morphology (Figure 8). If these curves suggest the presence of two separate arches, the composite arch is scored as present, which indicates a female (Figure 9).

Bruzek Method: Inferior Pelvis

Bruzek’s fourth area of analysis is the inferior pelvis, for which there are three criteria for scoring. The presence of external eversion of the ischiopubic ramus is more common in females, while males tend to exhibit less external eversion and may even curve inward at the superior end. The second criterion is the morphology of the ischiopubic ramus; females will tend to have pinched, narrow rami and in males this area

Fig. 7. Female greater sciatic notch.

will be broader and may feature a crista phallica on the anterior surface. The last criterion for the inferior pelvis area is general robusticity versus gracility. A robust inferior pelvis will be scored as male, while those exhibiting a higher degree of gracility will be scored as female (Figures 10 and 11).

Bruzek Method: Ischiopubic Proportions

The last aspect of the Bruzek method involves ischiopubic proportions. The pubis of the male pelvis will be shorter when compared to the ischium, while the female pubis will be longer when compared to the ischium (Figures 12 and 13). This criterion is assessed visually rather than being measured, though it does correspond with the ischiopubic index (Bruzek, 2002:162). When visual assessment alone was not enough to

Fig. 8. Male composite arch.

determine whether the pubis or the ischium was longer, measurements were taken to aid the determination but were not recorded.

Acetabulum Method

The last method, maximum diameter of the acetabulum, was also used to estimate sex in these samples (Figure 14). This measurement has been identified as a useful sex estimation method (Murphy, 2000), and should correspond with the maximum diameter of the femoral head measurement, which is also used to estimate sex (Bass,

2005). The acetabulum was used instead of the femur so that all assessments made are based only on the presence of the innominate.

The acetabulum measurement was taken following Murphy (2000). The tip on the fixed arm of a digital sliding caliper was placed at the intersection of the acetabular rim and the anterior border of the iliac crest, and the movable arm was moved around the

Fig. 9. Female composite arch.

rim until the maximum value was determined. A sectioning point was determined using all acetabular measurements based on the midpoint of the two means, following

Klepinger and Giles (1998). Those individuals whose measurements are greater than the sectioning point were scored as male, while those who fell below the sectioning point were scored as female.

Statistics

The methods from all three sources are compared in the following two chapters. For traits described above in which scores of present, absent, and indeterminate are given, Pearson’s Chi-square is used to determine concordance between morphology and biological sex. Greater sciatic notch and preauricular sulcus scores were also compared using Pearson’s Chi-square. Since these traits are nominal (with the exception

Fig. 10. Male inferior pelvis.

of the greater sciatic notch and preauricular sulcus, which are ordinal), a nonparametric test is the best option to compare rates of accurate sex determination. Pearson’s Chi- square is used to determine whether the distribution of the dependent variable differs across the categories of the independent variable (Levin and Fox, 2007). For these tests, a significant Chi-square value indicates that morphology differs between males and females. Significance of all Chi-square tests will be assessed at an alpha level of 0.05 (α

= 0.05).

Pearson’s Chi-square is also used in this research for the individual components of the Bruzek method, to compare biological sex with the observed morphological expressions. Again, significant results indicate morphological differences

Fig. 11. Female inferior pelvis.

between males and females. In addition, Pearson’s Chi-square is used to compare biological sex with the sex determined by the Standards and Bruzek methods. A significant test result in this case indicates that the method differentiates between the sexes.

Cohen’s kappa is used to compare intra- and inter-rater reliability. Since intra- and interobserver error studies were performed as a part of this research, Cohen’s kappa will be used to examine concordance between two assessments by one individual and assessments made by two different individuals (Landis and Koch, 1977). Cohen’s kappa

Fig. 12. Male ischiopubic proportions.

determines the likelihood of agreements between observations and observers occurring beyond what would be expected by chance (Sim and Wright, 2005).

Cohen’s kappa is a coefficient of agreement and is assessed so that κ = +1.00 indicates perfect concordance between observations, κ = 0 indicates that agreement between observations is equal to the agreement expected by chance (Cohen 1960).

Agreement is less than expected by chance when κ is equal to a negative number.

Significance of Cohen’s kappa will be assessed with an alpha level of 0.05 (α = 0.05).

The strength of agreement for each kappa value was determined so that a value less than

0.00 is poor, 0.00-0.20 is slight, 0.21-0.40 is fair, 0.41-0.60 is moderate, 0.61-0.80 is substantial, and 0.81-1.00 is almost perfect (Landis and Koch, 1977).

Fig. 13. Female ischiopubic proportions.

To determine whether there is a significant difference between mean acetabulum measurements of males and females, independent samples t-tests were performed. This is appropriate because these are ratio level data and parametric statistics can be used. The independent t-test was used in this instance because it is suited to the comparison of means of independent samples. A significant result for this test indicates that the mean maximum diameter of the acetabulum is different for males and females.

A paired samples t-test is utilized when a sample is measured twice or when there is a relationship between the measurements which are being compared, such as measurements of the right and left acetabula of the same individual. Paired sample t-tests were used to analyze intra- and interobserver reliability in acetabulum measurements. A significant result for this test would indicate that different means were obtained by one

Fig.14. Maximum diameter of the acetabulum.

observer taking measurements twice or by both observers taking measurements once in the studies of intra-and interobserver error respectively. For all t-tests, alpha was set at

0.05 (α = 0.05).

In addition to these tests, error rates will be computed for the acetabulum measurements using the method described by Klepinger (2006). It is important to establish error rates for sex determination methods because some individuals will likely classify as female when they are really male, often due to individual variation or inaccuracy of the method. This is critical information to obtain since a method may be highly reliable for a population while performing poorly on some individuals. When using sex determination methods on a population, we should be able to estimate the

45 number of individuals who are likely to be misclassified. In forensic anthropology, however, the focus is on identification of individuals, not populations, and it is of vital importance that we can testify to the reliability of our determinations.

CHAPTER IV

OBSERVER ERROR RESULTS

Introduction

This chapter will discuss the analysis of intra- and interobserver error performed for this study. Observer error analysis is important in determining the reliability of methods for data collection in all areas of scientific research. In order for a method to be reliable, its results must be replicable. If the results of a method cannot be replicated beyond the individual responsible for the creation of that method, it will not be useful for the purposes of scientific research. Reliability is tested here with intraobserver and interobserver error studies. The intraobserver error study was completed by comparing two observations of all three methods using the same individuals. These observations were completed within three months of one another. Analysis of interobserver error was completed by comparing the observations of a second observer with the author’s first observations.

The intraobserver error results are discussed first. Within this section, the results for the pelvic methods used in Standards for Data Collection will be evaluated, followed by the components of the Bruzek method and the overall results of the Bruzek method. Finally, the results of the acetabulum measurements will be discussed. Results of the interobserver error analysis will then be covered in the same order.

46 47

Intraobserver Error

Intraobserver error analyses were performed using Cohen’s kappa statistic and paired t-tests. Cohen’s kappa is used to determine agreement between observations.

When κ = +1.00, perfect concordance has been achieved for both observations. If κ = -

1.00, observations are perfectly discordant. As κ approaches zero, it becomes more likely that agreement occurred by chance. Since the rate of agreement between observations is the goal of this reliability study, this statistical test is appropriate. A significant κ indicates agreement that is unlikely to have occurred by chance. Analysis of the strength of agreement for each kappa value was done using Landis and Koch (1977), who suggest the following labels: poor (< 0.00), slight (0.00 – 0.20), fair (0.21 – 0.40), moderate (0.41

– 0.60), substantial (0.61 – 0.80), and almost perfect (0.81 – 1.00). The paired t-test is used when comparing data that are related in some way, such as collecting data from siblings or collecting data twice from the same individual. Since the acetabulum measurement was recorded at two different times for the same individuals for comparison of reliability, this test is the appropriate choice for this study. A significant t value indicates differences between the first and second measurements that are unlikely to be due to chance. Only the data from the collection at California State University, Chico, are used for this intraobserver error study. Both innominates were used when available and

18 to 26 individuals were analyzed for each trait. The results of the intraobserver error study are summarized in Table 1.

Methods from Standards for Data Collection

Concordance was substantial between observations for the ventral arc aspect

(Left: 85.7%, Right: 83.3%), subpubic concavity (L: 90.4%, R: 90%), ischiopubic ramus

TABLE 1. Intraobserver error results Intraobserver Error Left Right Kappa Significance n Kappa Significance n Standards for Data Collection Ventral Arc 0.716 <0.001 21 0.649 <0.001 18 Subpubic Concavity 0.798 <0.001 21 0.778 <0.001 20 Ischiopubic Ramus Ridge 0.688 <0.001 21 0.607 <0.001 21 Greater Sciatic Notch 0.487 <0.001 25 0.518 <0.001 26 Preauricular Sulcus 0.608 <0.001 24 0.367 <0.001 25 Sex Determination 0.931 <0.001 26 0.931 <0.001 25 Bruzek Method Negative Relief 0.906 <0.001 26 1.000 <0.001 26 Border 0.915 <0.001 26 0.900 <0.001 26 Piriform Tubercle 0.588 <0.001 22 0.690 <0.001 24 Preauricular Area Overall 0.664 <0.001 22 0.833 <0.001 24 Proportion 0.746 <0.001 25 0.639 0.001 26 Symmetry 0.735 <0.001 25 0.350 0.033 26 Contour 0.645 <0.001 25 0.552 <0.001 26 Greater Sciatic Notch Overall 0.682 <0.001 25 0.472 0.001 26 Composite Arch 0.257 0.184 25 0.194 0.102 25 Sacroiliac Pelvic Complex 0.861 <0.001 22 1.000 <0.001 24 Eversion 0.877 <0.001 19 0.881 <0.001 21 Morphology 0.757 <0.001 19 0.675 <0.001 21 Robusticity 0.810 <0.001 20 0.817 <0.001 21 Inferior Pelvis Overall 0.638 <0.001 18 0.646 <0.001 20 Ischiopubic Proportions 0.236 0.104 18 0.323 0.063 19 Ischiopubic Pelvic Complex 0.257 0.056 17 0.357 0.013 18 Bruzek Method Overall -- -- 17 1.000 <0.001 19

(L: 81%, R: 76%), and left preauricular sulcus (79.2%). Agreement was moderate for greater sciatic notch scores (L: 60%, R: 61.5%), and fair for the right preauricular sulcus criterion (64%).

When each of these methods was combined to make an estimation of sex for each individual, the first and second observations were concordant in 25 out of 26 individuals (96.2%) for the left innominate, resulting in an agreement of κ = 0.931. The right innominate also achieved an agreement of κ = 0.931 between observations, with the same scores assigned to 24 out of 25 individuals (92.3%). Both kappa values are statistically significant (p < 0.001). The kappa values for the combined criteria indicate almost perfect agreement between observations.

Bruzek Method

The Bruzek method is a combination of eleven components divided into five regions. The preauricular area is assessed through observation of negative relief, the type of border if negative relief is present, and the presence or absence of a piriform tubercle.

The greater sciatic notch is assessed through proportionality, symmetry, and contour, using lines drawn from the posterior inferior iliac spine to the ischial spine, and from the deepest part of the notch to that line. A composite arch is observed if the anterior contour of the auricular surface and the greater sciatic notch form two separate arches. The inferior pelvis is analyzed through the observation of external eversion, and ischiopubic morphology and robusticity. Ischiopubic proportions are assessed through comparison of the lengths of the pubis and ischium.

Concordance was almost perfect for negative relief of the preauricular area (L:

96.2%, R: 100%), border type (96.2% for each side), the combined preauricular area criteria for the right side (91.7%), external eversion (L: 94.7%, R: 95.2%), and robusticity of the inferior pelvis (L: 90%, R: 90.5%). Agreement was substantial for the right piriform tubercle (79.2%), the combined preauricular area criteria for the left side

(81.8%), greater sciatic notch proportion (L: 88%, R: 84.6%), notch symmetry for the left side (92%), notch contour for the left side (80%), the combined greater sciatic notch criteria for the left side (80%), inferior pelvis morphology (L: 89.5%, R: 95.7%), and the combined inferior pelvis criteria (L: 83.3%, R: 80%). A moderate level of concordance was achieved for the left piriform tubercle criterion (72.2%), greater sciatic notch contour for the right side (69.2%), and the combined greater sciatic notch criteria for the right side (69.2%). Agreement was fair for notch symmetry on the right side (88.5%), composite arch for the left side (76%), and ischiopubic proportions (L: 50%, R: 63.2%).

Concordance was slight for the right composite arch aspect (76%).

Bruzek Method Overall. When each of these components was combined to make a determination of sex, all 17 left innominates and 19 right innominates with all criteria present were assigned concordant determinations between the first and second observations using each innominate. However, sex could only be determined for one right innominate. The remaining individuals were placed in the indeterminate category, as at least one component for each observation was not in agreement with the other components. The result is an agreement coefficient of κ = 1.0 for the right side, which is statistically significant (p < 0.001) and an almost perfect level of agreement. This result is meaningless, however, because only one right innominate could be sexed using the full

Bruzek method. A kappa value could not be calculated for the left side, because all left innominates were placed in the indeterminate category. This means that, while all observations were in agreement, no sex determinations could be made. If the Bruzek method always categorizes most or all individuals as indeterminate, this is not a useful sex determination method.

The Bruzek method also includes the analysis of two groups of criteria: the sacroiliac pelvic complex and the ischiopubic pelvic complex. The sacroiliac pelvic complex is the combination of the preauricular area, greater sciatic notch, and composite arch criteria. For the left side, 21 out of 22 innominates (95.5%) were assigned concordant scores for the sacroiliac pelvic complex, as were all 24 (100%) right innominates, resulting in agreement values of κ = 0.861 and κ = 1.0 respectively, which are almost perfect levels of agreement. Both values are statistically significant (p <

0.001).

The ischiopubic pelvic complex is the combination of the inferior pelvis and ischiopubic proportion criteria. Eight out of 17 left innominates (47.1%) were assigned concordant scores, resulting in an agreement value of κ = 0.257. This value is not statistically significant (p = 0.056), but indicates a fair level of agreement between observations. For the right side, ten out of 18 innominates (55.6%) were assigned concordant scores, producing an agreement coefficient of κ = 0.357. This value is statistically significant (p = 0.013), and indicates a fair level of agreement between observations.

Acetabulum Method

Paired t-tests were performed to compare measurements of the maximum diameter of the acetabulum between the first and second observations. For the left acetabula, the mean maximum diameter was 54.16 mm for the first measurement and

54.90 mm for the second measurement. The result of the t-test was not statistically significant (t = -1.91; df = 23; p = 0.07). For the right acetabula, the mean maximum diameter for the first measurement was 55.20 mm and 55.62 mm for the second

52 measurement. This test was not statistically significant (t = -1.40; df = 23; p = 0.17).

Error between the first and second measurements is 1.37% (0.74 mm) for the left side and

0.76% (0.42 mm) for the right side, indicating that there is only a slight difference between these measurements.

Interobserver Error

Interobserver error analyses were performed using Cohen’s kappa statistic and paired t-tests. Since the purpose of this study is to determine rates of agreement between two observers, Cohen’s kappa is an appropriate statistical test. Again, analysis of the strength of agreement for kappa values was done using Landis and Koch (1977). A paired t-test is also an appropriate choice, as both observers recorded acetabulum measurements for the same individuals. As with the statistics in the intraobserver error section, a significant kappa value indicates agreement that is unlikely to be due to chance, and a significant t value indicates that the differences between measurements are unlikely to be due to chance. Only the data from the collection at California State University, Chico, are used for this interobserver error study. Both innominates were used by each observer and

11 to 17 individuals were assessed for each trait. The second observer is a physical anthropology graduate student in the same cohort as the author with approximately three years of osteological experience. These observations were compared with the author’s first observations in order to eliminate the bias of experience using the methods, since the author collected this data before using all three methods on two hundred individuals in the Bass Donated Skeletal Collection. The results of the interobserver error study are summarized in Table 2.

TABLE 2. Interobserver error results Interobserver Error Left Right Kappa Significance n Kappa Significance n Standards for Data Collection Ventral Arc 0.596 0.005 14 0.381 0.063 14 Subpubic Concavity 0.500 0.013 14 0.545 0.006 15 Ischiopubic Ramus Ridge 0.466 0.009 14 0.408 0.021 15 Greater Sciatic Notch 0.506 0.000 17 0.545 0.000 17 Preauricular Sulcus 0.118 0.437 17 0.177 0.235 16 Sex Determination 0.626 0.000 17 0.636 0.000 17 Bruzek Method Negative Relief 0.095 0.582 17 0.163 0.200 16 Border -0.107 0.334 17 0.000 1.000 16 Piriform Tubercle 0.255 0.104 15 0.065 0.558 17 Preauricular Area Overall -0.098 0.360 15 0.127 0.400 16 Proportion 0.393 0.029 17 0.095 0.582 17 Symmetry 0.137 0.221 17 0.074 0.360 17 Contour 0.550 0.012 17 0.504 0.010 17 Greater Sciatic Notch Overall 0.220 0.066 17 0.092 0.110 17 Composite Arch 0.210 0.181 16 0.035 0.605 15 Sacroiliac Pelvic Complex -0.077 0.533 14 -0.034 0.782 15 Eversion 0.122 0.377 12 0.082 0.439 14 Morphology 0.143 0.447 12 0.074 0.647 14 Robusticity 0.258 0.160 12 0.263 0.102 14 Inferior Pelvis Overall -0.080 0.591 12 -0.055 0.661 14 Ischiopubic Proportions 0.168 0.245 12 0.188 0.207 13 Ischiopubic Pelvic Complex 0.312 0.105 11 0.207 0.097 13 Bruzek Method Overall -- -- 12 -- -- 12

Methods from Standards for Data Collection

Concordance was moderate between observers for the left ventral arc aspect

(78.6%), subpubic concavity (L: 71.4%, R: 73.3%), ischiopubic ramus (L: 64.3%, R:

60%), and greater sciatic notch (L: 58.8%, R: 64.7%). Agreement was fair for the right

54 ventral arc aspect (64.3%). A slight level of concordance was achieved for the preauricular sulcus (L: 35.3%, R: 43.8%).

When all of these methods were combined to make sex determinations, 13 out of 17 innominates (76.5%) were assigned concordant determinations using either side.

For the left side the agreement value was κ = 0.626 and for the right side it was κ = 0.636.

Both of these values are statistically significant (p < 0.001). These kappa values indicate a substantial level of agreement between observers.

Bruzek Method

A moderate level of agreement was obtained for greater sciatic notch contour

(76.5% for each side). Concordance was fair for the left piriform tubercle criterion

(53.3%), notch proportion for the left side (64.7%), the combination of all greater sciatic notch criteria for the left side (41.2%), composite arch for the left side (50%), and robusticity of the inferior pelvis (50% for each side). Agreement was slight for negative relief of the preauricular area (L: 47.1%, R: 43.8%), border type on the right side

(12.5%), the piriform tubercle criterion for the right side (35.3%), the combination of all preauricular area criteria for the right side (62.5%), notch proportion for the right side

(47.1%), notch symmetry (L: 41.2%, R: 35.3%), the combination of all greater sciatic notch criteria for the right side (35.5%), composite arch for the right side (26.7%), external eversion (L: 50%, R: 42.9%), inferior pelvis morphology (L: 41.7%, R: 35.7%), and ischiopubic proportions (L: 41.7%, R: 46.2%). Concordance was poor for border type on the left side (17.6%), the combination of all preauricular area criteria on the left side

(60%), and the combination of all inferior pelvis criteria (L: 25%, R: 21.4%).

Bruzek Method Overall. When each of these components was combined to make a determination of sex, all 12 individuals with all criteria present were assigned concordant determinations between observers using each innominate. However, sex could not be determined for these individuals, as at least one component for each observation was not in agreement with the other components, which resulted in a score of indeterminate for all 12 individuals. A kappa value could not be calculated for either side.

Although agreement is high for the complete Bruzek method, the agreement was that sex could not be determined for any individual assessed by both observers. A method which cannot produce a sex determination for one out of 12 individuals may not be useful and is not necessarily reliable.

The Bruzek method also includes the analysis of two groups of criteria: the sacroiliac pelvic complex and the ischiopubic pelvic complex. The sacroiliac pelvic complex is the combination of the preauricular area, greater sciatic notch, and composite arch criteria. For the left side, 10 out of 14 innominates (71.4%) were assigned concordant scores for the sacroiliac pelvic complex, as were 13 out of 15 right innominates (86.7%), resulting in agreement values of κ = -0.077 and κ = -0.034 respectively. Neither value is statistically significant (p = 0.533 for the left side and p =

0.782 for the right side). Both values indicate a poor level of agreement between observers.

The ischiopubic pelvic complex is the combination of the inferior pelvis and ischiopubic proportion criteria. Eight out of 11 left innominates (72.7%) were assigned concordant scores, resulting in an agreement value of κ = 0.312. This value is not statistically significant (p = 0.105), but does indicate a fair level of agreement between

56 observers. For the right side, eight out of 13 innominates (61.5%) were assigned concordant scores, producing an agreement coefficient of κ = 0.207. This value is not statistically significant (p = 0.097), but it does reveal a fair level of agreement between observers.

Acetabulum Method

Paired t-tests were performed to compare measurements of the maximum diameter of the acetabulum between observers. For the left acetabula, the mean maximum diameter was 54.68 mm for the first observer and 53.77 mm for the second observer. The result of the t-test was statistically significant (t = 3.371; df = 15; p = 0.004). For the right acetabula, the mean maximum diameter was 54.97 mm for the first observer and 53.75 mm for the second observer. This test is statistically significant (t = 7.588; df = 16; p <

0.001). Error between measurements taken by the first and second observers is 1.66%

(0.91 mm) for the left side and 2.22% (1.22 mm) for the right side. While there is a significant difference between these measurements, it is slight and not necessarily meaningful, since both sides are within the range of normal measurement error between observers.

Summary and Conclusions

Agreement was high for each method in the intraobserver error study, indicating that there is a high degree of reliability when these methods are used multiple times by the same observer. All aspects of the Standards for Data Collection methods, including the sex determinations made by combining all of these aspects, were highly statistically significant in agreement. For the Bruzek method, statistically significant

57 agreement was not found for the composite arch and ischiopubic proportions aspects of this study. This was also the case for the ischiopubic pelvic complex, but this combination was approaching a significant level of agreement. When all aspects of the

Bruzek method were combined, all but one individual was placed in the indeterminate category for both observations. While this means that the observations were in agreement, it also means that only one sex determination was made using this method, making the use of this method questionable at best. All other aspects and combinations of the Bruzek method were in significant agreement. The acetabulum measurements were not significantly different between observations, indicating that this measurement can be recorded consistently by the same observer multiple times. Overall, intra-rater reliability is high for each of the methods tested in this study.

The interobserver error study revealed only a few areas of statistically significant agreement. The observers scored most of the Standards aspects consistently, resulting in statistically significant agreement for the left ventral arc, subpubic concavity, ischiopubic ramus ridge, the greater sciatic notch, and sex determinations using all of these aspects. For the Bruzek method, greater sciatic notch proportion was significant for the left side only, and greater sciatic notch contour was statistically significant in agreement for both sides. The only group of aspects for the Bruzek method which approached statistical significance in agreement was the greater sciatic notch combination. Both observers placed every individual in the indeterminate category when sex determinations were made using all aspects of the Bruzek method. While agreement was high for the combined Bruzek method, no sex determinations could be made, indicating once again that this method may be questionable in its present form. The

58 acetabulum measurements were significantly different between observers, but the differences were so small that they are not necessarily meaningful, since the differences were around one millimeter for each side. Overall, inter-rater reliability was low for the methods tested in this study.

The next chapter will address the accuracy in sex determinations made using each of these methods with a larger sample.

CHAPTER V

METHOD RESULTS

Introduction

Only the data from the University of Tennessee, Knoxville, are used for the following analyses. Of the 200 individuals used in this study, 132 are male (66%) and 68 are female (34%). Ages range from 24 to 99 years, with a mean of 58.2 years. Variation in ancestry is minimal for this sample. Whites make up 90% of the sample (180 individuals), seven percent of the sample is black (14 individuals), two percent of the sample is Hispanic (4 individuals), and one percent of the sample is of Native American or Asian descent (1 individual each).

Each individual was assessed using the pelvic methods presented in Standards for Data Collection (Buikstra and Ubelaker, 1994) before the Bruzek method and acetabulum measurements were recorded. The Standards and Bruzek methods were recorded at different times in an effort to minimize their influence on each other for those aspects which are similar for both methods.

Statistical analyses were performed for all nominal variables using Pearson’s chi-square tests. The strength of association between variables was determined by phi

(2x2 table) or Cramer’s V (>2x2 table). A significant chi-square indicates that there is a relationship between biological sex and expression of a trait, and phi and Cramer’s V indicate the strength of association between variables. These statistical tests are

59 60 appropriate for this analysis because it is important to understand whether or not there is a significant relationship between each variable or method and biological sex, as well as the strength of that relationship. The difference between acetabulum measurements was assessed using independent samples t-tests. A significant t-value indicates that acetabulum values are statistically different between sexes.

Results

First, the results for the methods recommended in Standards for Data

Collection will be presented, followed by each aspect of the Bruzek method, and then the acetabulum method. The results of the morphological methods are summarized in Table

3. The results for the acetabulum method will be presented in a separate table in that section.

Methods from Standards for Data Collection

Tables 4 and 5 summarize correct classifications and misclassifications. A ventral arc was present on the left side in 60 females (88.2%) and three males (2.3%;

Figure 15). For the right pubis, 62 females (92.5%) and two males (1.5%) displayed a ventral arc. One female (1.5%) lacked a ventral arc on the left side, as did 90 males

(69.2%), for a total of 45.5 percent of the sample. On the right side, one female (1.5%) and 99 males (76.2%) lacked a ventral arc. Of the remaining individuals, seven females

(10.3%) and 37 males (28.5%) displayed ambiguous morphology for the left side. Four females (6%) and 28 males (21.5%) scored as ambiguous for the right ventral aspect of the pubis. Two left pubes and four right pubes were unobservable.

TABLE 3. Results for morphological methods General Results Left Right

χ2 p ϕ or χ2 p ϕ or Method V V Standard Methods Ventral Arc 154.8 <0.001 0.884 167.4 <0.001 0.924 Subpubic Concavity 166.0 <0.001 0.913 167.2 <0.001 0.923 Ischiopubic Ramus Ridge 138.5 <0.001 0.834 144.7 <0.001 0.857 Greater Sciatic Notch 111.2 <0.001 0.746 93.9 <0.001 0.685 Preauricular Sulcus 116.8 <0.001 0.764 82.22 <0.001 0.646 Sex Determination 174.5 <0.001 0.934 182.8 <0.001 0.956 Bruzek Method Negative Relief 119.8 <0.001 0.774 71.77 <0.001 0.599 Border 13.42 0.001 0.473 12.08 0.0020.456 Piriform Tubercle 56.52 <0.001 0.532 40.04 <0.001 0.447 Preauricular Area Overall 82.86 <0.001 0.644 49.88 <0.001 0.499 Proportion 76.55 <0.001 0.619 93.88 <0.0010.685 Symmetry 45.55 <0.001 0.477 44.35 <0.0010.471 Contour 82.45 <0.001 0.642 68.86 <0.0010.587 Greater Sciatic Notch Overall 71.35 <0.001 0.597 70.86 <0.001 0.595 Composite Arch 86.78 <0.001 0.672 66.32 <0.001 0.583 Sacroiliac Pelvic Complex 53.93 <0.001 0.530 36.37 <0.001 0.432 Eversion 151.2 <0.001 0.874 137.1 <0.0010.836 Morphology 149.9 <0.001 0.868 146.2 <0.0010.864 Robusticity 152.5 <0.001 0.875 154.5 <0.0010.888 Inferior Pelvis Overall 143.8 <0.001 0.852 141.5 <0.001 0.850 Ischiopubic Proportions 149.4 <0.001 0.873 135.3 <0.001 0.835 Ischiopubic Pelvic Complex 136.4 <0.001 0.834 133.9 <0.001 0.831 Bruzek Method Overall 34.80 <0.001 0.417 23.91 <0.001 0.346

Comparison of the ventral arc aspect of the pubis with biological sex revealed a statistically significant relationship for the left side (χ2 = 174.5; df = 2; p < 0.001; N =

198), and the right side (χ2 = 167.4; df = 2; p < 0.001; N = 196). The association between biological sex and the presence or absence of a ventral arc indicates a very strong relationship for both left (V = 0.934; p < 0.001) and right sides (V = 0.924 p < 0.001).

TABLE 4. Percentages of correct classifications and misclassifications for females using morphological methods Classification Accuracy for Females Left Right Correctly Classified as Total Correctly Classified as Total Standards for Data Collection Classified Male Misclassified Classified Male Misclassified Ventral Arc 88.2 1.5 11.8 92.5 1.5 7.5 Subpubic Concavity 94.1 1.5 5.9 95.5 1.5 4.5 Ischiopubic Ramus Ridge 76.5 0 23.5 73.5 0 26.5 Greater Sciatic Notch 95.6 0 4.4 100 0 0 Preauricular Sulcus 72.1 27.9 27.9 60.5 39.5 39.5 Sex Determination 95.5 0 4.5 97.0 0 3.0 Bruzek Method Negative Relief 79.6 20.6 20.6 66.2 33.8 33.8 Border* 81.5 16.7 18.5 69.6 28.3 30.4 Piriform Tubercle 63.2 11.8 36.8 54.4 16.2 45.6 Preauricular Area Overall 45.6 5.9 54.4 29.4 10.3 70.6 Proportion 73.5 26.5 26.5 86.8 13.2 13.2 Symmetry 30.8 69.2 69.2 36.8 63.2 63.2 Contour 83.8 11.7 16.2 82.4 7.4 17.6 Greater Sciatic Notch Overall 30.9 7.3 69.1 36.8 2.9 63.2 Composite Arch 71.6 28.4 28.4 66.2 33.8 33.8 Sacroiliac Pelvic Complex 17.9 0 82.1 10.3 0 89.7 Eversion 88.1 9 11.9 86.6 10.4 13.4 Morphology 85.3 2.9 14.7 85.1 4.5 14.9 Robusticity 88.2 4.4 11.8 89.7 4.5 10.3 Inferior Pelvis Overall 76.1 3.0 23.9 74.6 3.0 25.4 Ischiopubic Proportions 98.5 1.5 1.5 98.5 1.5 1.5 Ischiopubic Pelvic Complex 75.8 1.5 24.2 75.8 1.5 24.2 Bruzek Method Overall 12.3 0 87.7 7.6 0 92.4 * Total N = 60 (left) and 58 (right)

TABLE 5. Percentages of correct classifications and misclassifications for males using non-metric methods Classification Accuracy for Males Left Right Correctly Classified as Total Correctly Classified as Total Standards for Data Collection Classified Female Misclassified Classified Female Misclassified Ventral Arc 69.2 2.3 30.8 76.2 1.5 23.0 Subpubic Concavity 77.9 3.1 22.1 86.8 3.1 23.8 Ischiopubic Ramus Ridge 77.1 3.1 22.9 81.4 1.6 18.6 Greater Sciatic Notch 19.7 37.8 80.3 21.1 37.1 78.9 Preauricular Sulcus 97.7 2.3 2.3 95.4 4.6 4.6 Sex Determination 53.0 2.3 47.0 65.2 1.5 34.8 Bruzek Method Negative Relief 95.5 4.5 4.5 90.9 9.1 9.1 Border* 83.3 16.7 16.7 83.3 16.7 16.7 Piriform Tubercle 52.3 13.6 47.7 47.0 13.6 53.0 Preauricular Area Overall 52.3 0.8 47.7 47.0 1.5 53.0 Proportion 87.9 12.1 12.1 84.1 15.9 15.9 Symmetry 100 0 0 97.7 2.3 2.3 Contour 58.3 17.4 41.7 56.1 22 43.9 Greater Sciatic Notch Overall 56.8 0 43.2 52.3 2.3 47.7 Composite Arch 92.8 7.2 7.2 89.8 10.2 10.2 Sacroiliac Pelvic Complex 41.6 0 58.4 30.7 0 69.3 Eversion 95.4 3.1 4.6 93.0 4.7 7.0 Morphology 84.7 3.1 15.3 86.8 3.1 13.2 Robusticity 90.8 3.8 9.2 90.7 3.1 9.3 Inferior Pelvis Overall 83.2 1.5 16.8 83.7 1.6 16.3 Ischiopubic Proportions 84.6 8.5 15.4 82.8 11.7 17.2 Ischiopubic Pelvic Complex 72.3 1.5 27.7 70.3 1.6 29.7 Bruzek Method Overall 28.2 0 71.8 21.0 0 79.0 * Total N = 60 (left) and 58 (right)

Ventral Arc

Left Right

Fig. 15. Ventral arc.

Both innominates show a statistically significant relationship between biological sex and presence or absence of the ventral arc trait. Presence of a ventral arc is highly indicative of the female sex, while absence of a ventral arc suggests a male.

A subpubic concavity was present in 64 females (94.1%) and four males

(3.1%) on the left side, and 64 females (95.5%) and four males (3.1%) on the right side

(Figure 16). One female (1.5%) lacked a concavity on both sides, while 102 left (77.9%) and 112 right (86.8%) male innominates also lacked a concavity. Ambiguous morphology was observed in three females (4.4%) and 25 males (19.1%) on the left side, and two females (3%) and 13 males (10.1%) on the right side. A concavity was unobservable in one left innominate and four right innominates.

Subpubic Concavity

Left Right

Fig. 16. Subpubic concavity.

A statistically significant relationship was revealed when the subpubic concavity was compared by biological sex for the left (χ2 = 166.0; df = 2; p < 0.001; N =

199) and the right innominates (χ2 = 167.2; df = 2; p < 0.001; N = 196). The relationship between subpubic concavity and biological sex is strong for the left (V = 0.913; p <

0.001) and right sides (V = 0.923; p < 0.001). Expression of subpubic concavity shows a statistically significant relationship with biological sex for both innominates. If a pubis exhibits subpubic concavity, it very likely belongs to a female, while a pubis lacking concavity will likely belong to a male.

The left ischiopubic ramus displayed a sharp ridge in 52 females (76.5%) and four males (3.1%; Figure 17.) On the right side, an ischiopubic ramus ridge was observed

Ischiopubic Ramus Ridge

Left Right

Fig. 17. Ischiopubic ramus ridge.

in 50 females (73.5%) and two males (1.6%). No females displayed a broad ischiopubic ramus on either side. A broad ramus was observed in 101 males (77.1%) on the left side and 105 males (81.4%) on the right side. Ambiguous morphology was observed in 16 females (23.5%) and 26 males (19.8%) on the left side, and 18 females (26.5%) and 22 males (17.1%) on the right side. The ischiopubic ramus was unobservable in one left and three right innominates.

A comparison of the ischiopubic ramus by biological sex revealed a statistically significant relationship for both the left (χ2 = 138.5; df = 2; p < 0.001; N =

199) and the right sides (χ2 = 144.7; df = 2; p < 0.001; N = 197). The relationship between these variables indicates a strong association for both left (V = 0.834; p < 0.001) and right

67 sides (V = 0.857; p < 0.001). The relationship between expression of the ischiopubic ramus ridge and biological sex is statistically significant, such that a broad, robust ramus is likely to belong to a male innominate, while a pinched, gracile ramus has a strong chance of belonging to a female innominate.

The greater sciatic notch scores clustered around the female, probable female, and ambiguous expressions; 174 individuals (87%) were placed in these categories using the left innominate and 172 individuals (86%) were placed in these categories using the right innominate (Figure 18). A score of one was assigned to 49 females (72.1%) and six

Greater Sciatic Notch

Left Right

Fig. 18. Greater sciatic notch.

68 males (4.5%) for the left notch, and 49 females (72.1%) and seven males (5.3%) on the right side. A score of two was assigned to 16 females (23.5%) and 44 males (33.3%) on the left side, and 19 females (27.9%) and 42 males (31.8%) on the right side. A score of three, traditionally considered ambiguous morphology, was assigned to three females

(4.4%) and 56 males (42.4%) on the left side, and 55 males (41.7%) on the right side. No females were assigned a score of three on the right side. Scores of four and five were not assigned to any females for either side. A score of four was assigned to 19 left notches

(14.4%) and 23 right notches (17.4%). Seven left notches (5.3%) and 5 right notches

(3.7%) were assigned a score of five.

Comparison of greater sciatic notch morphology by biological sex revealed a statistically significant relationship for the left (χ2 = 111.2; df = 4; p <0.001; N = 200) and right sides (χ2 = 93.9; df = 4; p <0.001; N = 200). The association between these variables indicates a strong relationship for both the left (V = 0.746; p <0.001) and right sides (V =

0.685; p <0.001). A wide greater sciatic notch is more likely to belong to a female than a male, while a narrow notch will only be found in males. This trait appears to be a better indicator for females than males, however, as the males in this sample exhibited expression at both ends of the scale.

A preauricular sulcus was present in 46 left (23.3%) and 52 right innominates

(26%; Figure 19). Three males (2.3%) displayed a preauricular sulcus on the left side, all of which were narrow and shallow. A preauricular sulcus was observed in six right male innominates (4.6%), five of which were narrow and shallow while the remaining sulcus was narrow and deep. Eight females (11.8%) displayed a wide, deep sulcus on the left side and three females (4.5%) displayed the same type of sulcus on the right side. A wide,

Preauricular Sulcus

Left Right

Fig. 19. Preauricular Sulcus.

shallow sulcus was observed in 25 left innominates (36.8%) and 23 right innominates

(34.8%). Nine females (13.2%) displayed a narrow, deep sulcus on the left side, and five females (7.6%) displayed this type of sulcus on the right side. Seven left female innominates (10.3%) and nine right female innominates (13.6%) exhibited a narrow, shallow sulcus. No sulcus was observed in 19 left innominates of females (27.9%) and

129 left innominates of males (97.7%), and 26 right innominates (39.5%) and 125 right innominates (95.4%). Three right preauricular surfaces were unobservable.

Absence or expression of a preauricular sulcus shows a statistically significant relationship with biological sex for both left (χ2 = 116.8; df = 4; p < 0.001; N = 200) and

70 right sides (χ2 = 82.22; df = 4; p < 0.001; N = 197). These values indicate a strong relationship between biological sex and expression of a preauricular sulcus for the left

(V= 0.764; p < 0.001) and right side (V = 0.646; p < 0.001). Any preauricular sulcus form is more likely to indicate a female than a male. While the absence of a sulcus in the preauricular area is more likely indicative of the male sex, some females also lack preauricular sulci.

When sex determinations were made using all of the Standards methods together on the left side, 65 females (95.6%) were correctly classified as female and 70 males (53%) were correctly classified as male (Figure 20). Only three females (4.4%) were placed in the indeterminate category, while no females were misclassified as male.

Three males (2.3%) were misclassified as female, and 59 males (44.7%) were placed in the indeterminate category. Using the right side, 66 females (97%) were correctly classified as female and 86 males (65.2%) were correctly classified as male. Two females

(3%) were placed in the indeterminate category and no females were misclassified as male. Two males (1.5%) were misclassified as female and 44 males (33.3%) were placed in the ambiguous category.

When sex determinations were made using these methods together, analysis produced a statistically significant result for the left (χ2 = 174.5; df = 2; p < 0.001; N =

200) and for right (χ2 = 182.8; df = 2; p < 0.001; N = 200) innominates. These values indicate a very strong relationship between biological sex and sex determinations made using the methods in Standards for Data Collection for both left (V = 0.934; p < 0.001) and right sides (V = 0.956; p < 0.001). In summary, there is a statistically significant relationship between biological sex and the sex determinations made using these

Sex Determinations

Left Right

Fig. 20. Sex estimations using the Standards for Data Collection (Buikstra and Ubelaker, 1994) methods.

methods. When these aspects of the innominates are combined in order to develop an estimation of sex, there is a very high likelihood that the estimation will be accurate.

Bruzek Method

Preauricular Surface. The first criterion of the preauricular surface is the presence or absence of negative relief. Negative relief was present in 54 female left innominates (79.4%) and six male left innominates (4.5%), and 45 female right innominates (66.2%) and 12 male right innominates (9.1%; Figure 21). A smooth preauricular area without negative relief was observed in 14 females (20.6%) and 126

Preauricular Area: Negative Relief

Left Right

Fig. 21. Preauricular area: negative relief.

males (95.5%) on the left side. This morphology was found on the right side in 23 females (33.8%) and 120 males (90.9%).

When negative relief was compared with biological sex, a statistically significant relationship was found for the left (χ2 = 119.8; df = 1; p < 0.001; N = 200) and right sides(χ2 = 71.77; df = 1; p < 0.001; N = 200). Association between negative relief and biological sex indicates a strong relationship for the left (ϕ = 0.774; p < 0.001) and right sides (ϕ = 0.599; p < 0.001). When present, individuals with negative relief in the preauricular area are more likely to be female, and those without negative relief are more likely to be male.

The second criterion of the preauricular surface relates to the border of the negative relief when that trait is present. Since 70 percent of left and 71.5 percent of right innominates did not exhibit negative relief, those innominates were removed from consideration for this criterion (Figure 22). A closed border was present in 44 females

Preauricular Area: Border Type

Left Right

Fig. 22. Preauricular area: border type.

(81.5%) and one male (16.7%) for the left innominates, and 32 females (69.6%) and two males (16.7%) for the right innominates. Nine females (16.7%) and five males (83.3%) displayed an open border on the left innominate, while an open border was present in 13 females (28.3%) and ten males (83.3%) on the right side. For each side, one female was

74 placed in the indeterminate category (1.9% for the left side and 2.2% for the right). No males were scored as indeterminate for either side

When negative relief border type was compared by biological sex, a statistically significant relationship was revealed for the left side (χ2 = 13.42; df = 2; p =

0.001; N = 60) and the right side (χ2 = 12.08; df = 2; p = 0.002; N = 58). This relationship is moderately strong for the left (V = 0.473; p = 0.001) and right innominates (V = 0.456; p = 0.002). When negative relief is present in the preauricular area, border type is significantly related to biological sex. Most females exhibit a closed border if negative relief is present, while males are more likely to have an open border when negative relief is present in the preauricular area.

The last preauricular surface criterion is the presence or absence of a piriform tubercle. A piriform tubercle was present in eight female left innominates (11.8%) and 69 male left innominates (52.3%), and 11 female right innominates (16.2%) and 62 male right innominates (47%; Figure 23). Absence of a piriform tubercle was observed in 43 females (63.2%) and 18 males (13.6%) on the left side, and 37 females (54.4%) and 18 males (13.6%) on the right side. Intermediate morphology was observed in 17 female left innominates (25%) and 45 male left innominates (34.1%), and in 20 female right innominates (29.4%) and 52 male right innominates (39.4%).

Analysis of the piriform tubercle in relation to biological sex resulted in a statistically significant result for the left innominate (χ2 = 56.52; df = 2; p < 0.001; N =

200) as well as the right (χ2 = 40.04; df = 2; p < 0.001; N = 200). The association between these variables indicates a moderately strong relationship on the left side (V = 0.532; p <

0.001) and the right side (V = 0.447; p < 0.001). When a piriform tubercle is present on

Preauricular Area: Piriform Tubercle

Left Right

Fig. 23. Preauricular area: piriform tubercle.

an individual, that individual is significantly more likely to be male than female.

However, the intermediate form of the tubercle can also be found with a high degree of regularity in both sexes. In isolation, this aspect would not be a very reliable sex indicator.

Since true sex determinations can only be made when all three components agree with each other, sex could only be reliably determined for 52.5 percent of the sample (100 individuals) using the left side and 45.5 percent of the sample (82 individuals) using the right side (Figure 24). On the left side, females were correctly classified in 31 cases (45.6%) and males were correctly classified in 69 cases (52.3%).

Females were correctly classified using the right side in 20 cases (29.4%) and males were

Preauricular Area Overall

Left Right

Fig. 24. Preauricular area overall.

correctly classified using the right side in 62 cases (47%). Four left female innominates

(5.9%) and seven right female innominates (10.3%) were misclassified as male. One left male innominate (0.76%) and two right male innominates (1.5%) were misclassified as female. Preauricular area criteria could not determine sex in 33 female left innominates

(48.5%), 62 male left innominates (47%), 41 female right innominates (60.2%), and 68 male right innominates (51.5%).

When all three preauricular area components were considered together and compared with biological sex, analysis revealed a statistically significant relationship for the left (χ2 = 82.86; df = 2; p < 0.001; N = 200) and right sides (χ2 = 49.88; df = 2; p <

0.001; N = 200). The association reveals a moderately strong relationship between

77 biological sex and the preauricular area criteria on the left (V = 0.644; p < 0.001) and right sides (V = 0.499; p < 0.001). There is a low rate of misclassification for individuals whose sex can be estimated using these criteria. However, sex could not be determined for about half of the innominates in the sample, indicating that this combination of traits may not be the best for determining sex, or that determinations may be constrained by requiring the agreement of all three traits.

Greater Sciatic Notch. The first criterion to consider when examining the greater sciatic notch with this method is proportionality. Proportionality was equal in 50 female left innominates (73.5%) and 16 male left innominates (12.1%), and in 59 female right innominates (86.8%) and 21 male right innominates (15.9%; Figure 25). A disproportionate greater sciatic notch was observed in 18 female left innominates (26.5%) and 116 male left innominates (87.9%), and nine female right innominates (13.2%) and

111 male right innominates (84.1%).

When proportionality was compared by biological sex, a statistically significant relationship was found for the left (χ2 = 76.55; df = 1; p < 0.001; N = 200) and right notches (χ2 = 93.88; df = 1; p < 0.001; N = 200). The association between these variables is strong for the left (ϕ = 0.619; p < 0.001) and right sides (ϕ = 0.685; p <

0.001). There is a statistically significant relationship between biological sex and proportionality, such that a proportional greater sciatic notch is indicative of a female, while a notch that is not proportional is indicative of a male.

The second criterion of the greater sciatic notch is symmetry. On the left side,

21 females (30.8%) had symmetrical notches (Figure 26). No left male greater sciatic

Greater Sciatic Notch: Proportion

Left Right

Fig. 25. Greater sciatic notch: proportion.

notches were symmetrical. For the right side, 25 females (36.8%) and three males (2.3%) had symmetrical notches. Asymmetry was observed in 47 female left innominates

(69.2%) and 132 male left innominates (100%), and in 43 female right innominates

(63.2%) and 129 male right innominates (97.7%).

Comparison of greater sciatic notch symmetry by biological sex revealed a statistically significant relationship for the left (χ2 = 45.55; df = 1; p < 0.001; N = 200) and right notches (χ2 = 44.35; df = 1; p < 0.001; N = 200). The association between these variables suggests a moderately strong relationship for the left (ϕ = 0.477; p < 0.001) and right sides (ϕ = 0.471; p < 0.001). While a symmetrical greater sciatic notch is highly

Greater Sciatic Notch: Proportion

Left Right

Fig. 26. Greater sciatic notch: symmetry.

indicative of a female, and males are statistically likely to have asymmetrical notches, females also have a high rate of asymmetry. This indicates that symmetry may not be an adequate sex indicator, regardless of the statistically significant relationship between symmetry and biological sex.

Contour of the posterior portion of the greater sciatic notch is the last criterion examined for the greater sciatic notch. For left innominates, 83.8 percent of females and

17.4 percent of males (57 females and 23 males) had an enclosed posterior contour

(Figure 27). The contour was enclosed in right innominates in 82.4 percent of females and 22 percent of males (56 females and 29 males). A notch contour that extended beyond the line was observed in 11.7 percent of females and 58.3 percent of males (8

Greater Sciatic Notch: Proportion

Left Right

Fig. 27. Greater sciatic notch: contour.

females and 77 males) for left innominates, and 7.4 percent of females and 56.1 percent of males (5 females and 74 males) for right innominates. In cases where part of the contour extended and part was enclosed, individuals were scored as indeterminate. This type of morphology was observed in 4.4 percent of females and 24.2 percent of males (3 females and 32 males) on the left side, and 10.3 percent of females and 22 percent of males (7 females and 29 males) on the right side.

Comparison of contour types by biological sex revealed a statistically significant relationship for the left (χ2 = 82.45; df = 2; p < 0.001; N = 200) and right notches (χ2 = 68.86; df = 2; p < 0.001; N = 200). The association between these variables is moderate for the left (V = 0.642; p < 0.001) and right sides (V = 0.587; p < 0.001).

When the contour of the posterior portion of the greater sciatic notch extends beyond a line drawn using the deepest part of the notch and the ischial spine, the notch is most likely male, while a notch enclosed by the same line is most likely a female. While there is less variation in contour expression for female innominates, contour expression is much more varied in males, making this a better sex indicator for females than for males.

A combination of all three greater sciatic notch criteria resulted in true sex determinations for 50.5 percent of individuals using the left and 49.5 percent of individuals using the right side. For the left side, 21 females (30.9%) were correctly classified as female and 75 males (56.8%) were correctly classified as male (Figure 28).

Greater Sciatic Notch Overall

Left Right

Fig. 28. Greater sciatic notch overall.

For the right innominate, 25 females (36.8%) were correctly classified as female and 69 males (52.3%) were correctly classified as male. Using the left side, no males were misclassified as female, and 5 females (7.3%) were misclassified as male. Three males

(2.3%) were misclassified as female and two females (2.9%) were misclassified as male using the right innominate. Cases where greater sciatic notch criteria were not in agreement were assigned the category of indeterminate sex. For the left innominate, 42 females (61.8%) and 57 males (43.2%) were placed in the indeterminate category. Using the right innominate, 41 females (60.3%) and 60 males (45.5%) were classified as indeterminate.

When all greater sciatic notch criteria are considered together and compared with biological sex, a statistically significant relationship was found for the left (χ2 =

71.35; df = 2; p < 0.001; N = 200) and right notches (χ2 = 70.86; df = 2; p < 0.001; N =

200). The association between these variables indicates that this relationship is moderately strong for the left (V = 0.597; p < 0.001) and right sides (V = 0.595; p <

0.001). All individuals for whom sex determinations could be made based on all three greater sciatic notch criteria were correctly classified, but a sex determination could not be made for a large percentage of the sample. While this group of traits is very accurate when they are all in agreement, the high prevalence of individuals in the indeterminate group indicates that agreement between all three criteria may be too constraining for sex determinations.

Composite Arch. When the arch formed by the anterior chord of the greater sciatic notch is separate from the arch formed by the anterior aspect of the auricular surface of the innominate, that innominate is said to possess a composite arch. In cases

83 where these arches combine to form a single arch, the composite arch is absent. The composite arch was present on the left innominates of 48 females (71.6%) and nine males

(7.2%), and 45 females (66.2%) and 13 males (10.2%) on the right side (Figure 29). A composite arch was absent in 19 female left innominates (28.4%) and 116 male left innominates (92.8%), and 23 female right innominates (33.8%) and 114 male right innominates (89.8%). The composite arch criterion was unobservable in eight left innominates and five right innominates.

Composite Arch

Left Right

Fig. 29. Composite arch.

Comparison of composite arch presence or absence between biological sexes revealed a statistically significant relationship for the left (χ2 = 86.78; df = 1; p < 0.001; N

= 192) and right sides (χ2 = 66.32; df = 1; p < 0.001; N = 195). The association between these variables is strong for the left side (ϕ = 0.672; p < 0.001) and moderately strong for the right side (ϕ = 0.583; p < 0.001). There is a statistically significant relationship between biological sex and the presence or absence of a composite arch. While the females in this study tend to exhibit a composite arch much more often than males, this trait seems to be a better indicator for males than it is for females, due to the higher percentage of males without a composite arch.

Inferior Pelvis. External eversion of the ischiopubic ramus is the first criterion of the inferior pelvis examined with the Bruzek method. External eversion was present in

59 female left innominates (88.1%) and four male left innominates (3.1%), and 58 female right innominates (86.6%) and six male right innominates (4.7%; Figure 30). Absence of eversion was observed in six females (9%) and 125 males (95.4%) on the left side, and seven females (10.4%) and 120 males (93%) on the right side. Intermediate morphology was observed in two females (3%) and two males (1.5%) on the left side, and two females (3%) and three males (2.3%) on the right side. Two left innominates and four right innominates were unobservable for this criterion.

Comparison between biological sex and external eversion revealed a statistically significant relationship for the left (χ2 = 151.2; df = 2; p < 0.001; N = 198) and right innominates (χ2 = 137.1; df = 2; p < 0.001; N = 196). The relationship between these variables is very strong for the left (V = 0.874; p < 0.001) and right sides (V =

0.836; p < 0.001). The relatively high rate of eversion in females and lack of eversion in

Inferior Pelvis: External Eversion

Left Right

Fig. 30. Inferior pelvis: external eversion.

males, together with the low rate of intermediate forms, suggests that external eversion of the ischiopubic ramus performs well as a sex indicator.

Morphology is the second criterion of the inferior pelvis used in the Bruzek method. A pinched, narrow ischiopubic ramus was present in 85.3 percent of female left innominates and 3.1 percent of male left innominates (58 females and four males), and

85.1 percent of female right innominates and 3.1 percent of male right innominates (57 females and four males; Figure 31). A broad ischiopubic ramus was observed in 2.9 percent of female left innominates and 84.7 percent of male left innominates (two females and 111 males), and 4.5 percent of female right innominates and 86.8 percent of male right innominates (three females and 112 males). Intermediate morphology was

Inferior Pelvis: Morphology

Left Right

Fig. 31. Inferior pelvis: morphology.

present in eight females (11.7%) and 16 males (12.2%) on the left side, and seven females (10.4%) and 13 males (10.1%) on the right side. One left innominate and four right innominates were unobservable for this criterion.

The comparison of biological sex and morphology of the inferior pelvis revealed a statistically significant relationship for the left (χ2 = 149.9; df = 2; p < 0.001; N

= 199) and right sides (χ2 = 146.2; df = 2; p < 0.001; N = 196). This relationship is very strong on the left (V = 0.868; p < 0.001) and right sides (V = 0.864; p < 0.001). A pinched, narrow ischiopubic ramus is highly indicative of a female, and a broad ramus, especially if it exhibits a crista phallica, is highly indicative of a male. While quite a few

87 individuals were placed in the indeterminate category, the correct classification rate is high for morphology of the inferior pelvis.

The final criterion for the inferior pelvis is robusticity. Gracility was observed in 60 females (88.2%) and five males (3.8%) for the left ischiopubic ramus, and 60 females (89.6%) and four males (3.1%) for the right ischiopubic ramus (Figure 32). A robust ischiopubic ramus was present in three female left innominates (4.4%) and 119

Inferior Pelvis: Robusticity

Left Right

Fig. 32. Inferior pelvis: robusticity.

male left innominates (90.8%), and three female right innominates (4.5%) and 117 male right innominates (90.7%). Five females (7.4%) and seven males (5.3%) were intermediate with regard to robusticity for the left innominate, as were four females (6%)

88 and eight males (6.2%) for the right. One left innominate and four right innominates were unobservable for this criterion.

A comparison between biological sex and expression of robusticity revealed a statistically significant relationship for the left (χ2 = 152.5; df = 2; p < 0.001; N = 199) and right sides (χ2 = 154.5; df = 2; p < 0.001; N = 196). The relationship for these variables is very strong for the left (V = 0.875; p < 0.001) and right sides (V= 0.888; p <

0.001). When the ischiopubic ramus is robust, there is a significant likelihood of being a male, while a gracile ischiopubic ramus is more likely to be a female. The low rate of intermediate forms, in addition to the high rate of correct classifications, suggests that morphology of the inferior pelvis serves as a good sex indicator.

Combination of all three inferior pelvis criteria resulted in true sex determinations for 82.9 percent of left innominates and 82.6 percent of right innominates.

For the left innominate, 51 females (76.1%) were correctly classified as female and 109 males (83.2%) were correctly classified as male (Figure 33). The right side yielded a correct classification rate of 74.6 percent (50 individuals) for females and 83.7 percent

(108 individuals) for males. Innominates for which all three criteria were not in agreement were assigned to the indeterminate category. Individuals in this category included 14 females (20.9%) and 20 males (15.3%) for left innominates, and 15 females

(23.4%) and 19 males (14.7%) for right innominates. Two females (3%) were misclassified as male for each side. The rate of misclassification for males was 1.5 percent (2 innominates) for the left side and 1.6 percent (2 innominates) for the right side.

Sex determinations could not be made for two left innominates (1% of the total sample

Inferior Pelvis Overall

Left Right

Fig. 33. Inferior pelvis overall.

size) and four right innominates (2% of the total sample size) due to unobservable criteria.

When all three inferior pelvis criteria are combined and compared with biological sex, the result was statistically significant for the left (χ2 = 143.8; df = 2; p <

0.001; N = 198) and right sides (χ2 = 141.5; df = 2; p < 0.001; N = 196). The association indicates a very strong relationship for the left (V = 0.852; p < 0.001) and right sides (V =

0.850; p < 0.001). The combination of inferior pelvis traits performs well as a sex indicator, due to the high rate of correct classifications. The rate of indeterminate forms was relatively high, but is much lower than for either the preauricular area or greater sciatic notch combinations.

Ischiopubic Proportion. The last part of the Bruzek method examines ischiopubic proportion. The pubis was longer in 98.5 percent of female left innominates and 8.5 percent of male left innominates (65 females and 11 males), and 98.5 percent of female right innominates and 11.7 percent of male right innominates (65 females and 15 males; Figure 34). One female (1.5%) and 110 males (84.6%) had a longer left ischium, while the right ischium was longer in one female (1.5%) and 106 males (82.8%). No

Ischiopubic Proportions

Left Right

Fig. 34. Ischiopubic proportions.

females had equal ischiopubic proportions on either side. Nine males (6.9%) had equal ischiopubic proportions on the left side, and seven males (5.5%) had equal proportions on

91 the right side. Four left innominates and six right innominates were unobservable for this criterion.

When ischiopubic proportions were compared by biological sex, a statistically significant relationship was revealed for the left (χ2 = 149.4; df = 2; p < 0.001; N = 196) and right innominates (χ2 = 135.3; df = 2; p < 0.001; N = 194). The relationship between these variables is very strong for the left (V = 0.873; p < 0.001) and right sides (V =

0.835; p < 0.001). Females are more likely to exhibit a longer pubis, while males tend to have a longer ischium. While ischiopubic proportion appears to be a good sex indicator in general, it performs best for females, as only one female exhibited male morphology.

Bruzek Method Overall. When all components of the Bruzek method were considered together, sex determinations were made based on the agreement of all criteria when each component was available for analysis. Only 43 individuals (22.8%) could be designated as male or female using the left side, while the right side produced sex determinations for only 31 individuals (16.3%; Figure 35). Eight females (12.3%) were correctly classified as female and 35 males (28.2%) were correctly classified as male using the left innominate. For the right innominate, five females (7.6%) were correctly classified as female and 26 males (21%) were correctly classified as male. There were no cases of females being misclassified as males or males misclassified as females for either side when all Bruzek criteria were used. However, since all criteria must be in agreement for this method to provide true sex determinations, the majority of individuals were placed in the indeterminate category. For the left innominate, sex could not be determined in 57 females (87.7%) and 89 males (71.8%). For the right innominate, sex could not be determined for 61 females (92.4%) and 98 males (79%). Eleven left

Bruzek Method Overall

Left Right

Fig. 35. Sex estimations using the Bruzek (2002) method.

innominates and ten right innominates were unobservable for at least one criterion, so they could not be included in this analysis.

The comparison between biological sex and sex determined using the Bruzek method was statistically significant for the left (χ2 = 35.01; df = 2; p < 0.001; N = 189) and right sides (χ2 = 24.16; df = 2; p < 0.001; N = 190). The relationship between these variables is moderately strong for the left (V = 0.430; p < 0.001) and right sides (V =

0.357; p < 0.001). While there is a statistically significant relationship between biological sex and the sex determinations made using the Bruzek method, this relationship is deceptive, since sex could not be estimated for the majority of individuals in this study.

However, all sex determinations that could be made were accurate.

Analysis of the sacroiliac pelvic complex involves combining scores for the preauricular area, greater sciatic notch, and composite arch to make sex determinations.

Estimations could be made for 64 left innominates (33.3%) and 46 right innominates

(23.6%) using the sacroiliac pelvic complex (Figure 36). For the left side, 12 females

(17.9%) were correctly classified as female and 52 males (41.6%) were correctly

Sacroiliac Pelvic Complex

Left Right

Fig. 36. Sex estimations using the sacroiliac pelvic complex of the Bruzek (2002) method.

classified as male. The right innominate was correctly classified for seven females

(10.3%) and 39 males (30.7%). No misclassifications were made for either sex using either innominate. Indeterminate scores were given to 55 female left innominates (82.1%) and 73 male left innominates (58.4%), and 61 female right innominates (89.7%) and 88

94 male right innominates (69.3%). Eight left innominates and five right innominates were unobservable for at least one criterion in this complex and could not be considered for this analysis.

A comparison between the sacroiliac pelvic complex scores and biological sex was statistically significant for the left (χ2 = 53.93; df = 2; p < 0.001; N = 192) and right sides (χ2 = 36.37; df = 2; p < 0.001; N = 195). This relationship is moderately strong for the left (V = 0.530; p < 0.001) and right sides (V = 0.432; p < 0.001). As with the full

Bruzek method, there is a high prevalence of individuals for whom sex determinations could not be made. The correct classification rate is higher for this combination, however, and again estimations were accurate for all individuals for whom a sex determination could be made.

Analysis of the ischiopubic pelvic complex involves combining the inferior pelvis and ischiopubic proportion criteria. For the left innominate, 50 females (75.8%) were correctly classified as female and 94 males (72.3%) were correctly classified as male (Figure 37). Fifty female right innominates (75.8%) were correctly classified as female and 90 male right innominates (70.3%) were correctly classified as male. One female (1.5%) was misclassified as male on each side. Two males (1.5% for the left side and 1.6% for the right side) were misclassified as female on each side. A score of indeterminate was assigned to 15 females (22.7%) and 34 males (26.2%) for the left innominate, and 15 females (22.7%) and 36 males (28.1%) for the right innominate. Four left innominates and six right innominates were scored as unobservable on at least one ischiopubic complex criterion and were removed from consideration.

Ischiopubic Pelvic Complex

Left Right

Fig. 37. Sex estimations using the ischiopubic pelvic complex of the Bruzek (2002) method.

A comparison of ischiopubic pelvic complex scores with biological sex revealed a statistically significant relationship for the left (χ2 = 136.4; df = 2; p < 0.001; N

= 196) and right sides (χ2 = 133.9; df = 2; p < 0.001; N = 194). This relationship is very strong for the left (V = 0.834; p < 0.001) and right sides (V = 0.831; p < 0.001). The ischiopubic pelvic complex performed relatively well in making sex determinations, as it was able to make sex estimations for a much greater percentage of the sample than either the sacroiliac pubic complex or the Bruzek method as a whole. However, a small percentage of individuals were inaccurately sexed by this complex, and the number of individuals in the indeterminate category is still fairly high.

The Bruzek Method: Revised

Individual aspects of the Bruzek method had high rates of correct classifications in all but a few cases. When all of the criteria were combined, however, the majority of individuals were placed in the indeterminate category.

Since it is unlikely that all eleven traits are weighted equally, the test was performed again by comparing estimations made by removing the four criteria with the highest error rates (border type, notch proportion and symmetry, and composite arch). If all seven of the remaining criteria were in agreement, a determination was made; if one of these seven was not in agreement, the individual was placed in the indeterminate category. For the left side, 27 females (39.7%) and 40 males (30.3%) were correctly classified (see Table 6 and Figure 38). One male (0.8%) was misclassified as a female and no females were misclassified as male. Of those placed in the indeterminate category,

TABLE 6. Results for the revised Bruzek method 7 Best Criteria 7 of 11 Criteria Left Right Left Right Chi Square 69.7 54.2 172.2 169.6 Cramer's V 0.591 0.521 0.939 0.921 p <0.001 <0.001 <0.001 <0.001 Correctly Classified Females 39.7% 30.9% 88.2% 86.8% Females Classified as Male 0% 0% 4.4% 2.9% Total Misclassified Females 60.3% 69.1% 11.8% 13.2% Correctly Classified Males 30.3% 25% 97.7% 94.7% Males Classified as Female 0.8% 0.8% 0.8% 1.5% Total Misclassified Males 68.9% 74.2% 2.3% 5.3%

91 (68.9%) were male and 41 (60.3%) were female. For the right side, 21 females

(30.9%) and 33 males (25%) were correctly classified. As with the left side, one male

7 Best Bruzek Criteria

Left Right

Fig. 38. Sex estimations using the seven best Bruzek (2002) criteria.

(0.8%) was incorrectly classified as female and no females were incorrectly classified as male. Of the individuals placed in the indeterminate category, 47 (69.1%) were female and 98 (74.2%) were male. For the sample as a whole, only one individual was incorrectly classified as the opposite sex using these seven criteria.

The comparison between biological sex and sex determinations made using only the seven criteria with the lowest error rates revealed a statistically significant relationship for the left side (χ2 = 69.7; df = 2; p < 0.001; N = 200) and the right side (χ2 =

54.2; df = 2; p < 0.001; N = 200). This relationship is moderately strong for the left side

(V = 0.591; p < 0.001) and the right side (V = 0.521; p < 0.001). There is a statistically significant relationship between biological sex and sex determinations using the seven

Bruzek criteria with the lowest error rates. While there are still quite a few individuals placed in the indeterminate category using only these criteria, the percentage is lower than for the original Bruzek method.

Since an ambiguous determination is not useful, this method was tested again with less strict requirements. When all components of the Bruzek method were considered together, sex determinations were made based on the agreement of seven or more of the 11 criteria when all criteria were present. If less than seven criteria were in agreement for an individual, that individual was placed in the indeterminate category. For the left side, 60 females (88.2%) and 129 males (97.7%) were correctly classified (Figure

39). Three females (4.4%) were misclassified as male and one male (0.8%) was

Revised Bruzek Method

Left Right

Fig. 39. Sex estimations using the revised Bruzek method.

99 misclassified as female. Of those placed in the indeterminate category, five (7.4%) were females and two (1.5%) were males. For the right side, 59 females (86.8%) and 125 males (94.7%) were correctly classified. Two females (2.9%) were misclassified as male and two males (1.5%) were misclassified as female. Seven females (10.3%) and five males (3.8%) were placed in the indeterminate category.

A comparison between biological sex and sex determined using this proposed revision of the Bruzek method revealed a statistically significant relationship on the left side (χ2 = 176.2; df = 2; p < 0.001; N = 200) as well as the right (χ2 = 169.6; df = 2; p <

0.001; N = 200). This relationship is very strong for the left side (V = 0.939; p < 0.001) and the right side (V = 0.921; p < 0.001). There is a statistically significant relationship between biological sex and the sex determinations made using this revised version of the

Bruzek method for the skeletal remains examined for this research. When at least seven aspects of the Bruzek criteria are in agreement, there is a very high likelihood that the sex determination will be accurate.

Acetabulum Method

The mean maximum diameter for left acetabula is 57.58 mm for males (N =

131) and 51.41 mm for females (N = 66), and 57.69 mm for males (N = 130) and 51.49 mm for females (N = 65) for the right acetabula (see Table 7). Comparison of maximum diameter of the acetabulum by biological sex resulted in a significant difference for both the left (t = 14.27; df = 195; p < 0.001; N = 197) and right acetabula (t = 13.541; df = 193; p < 0.001; N = 195). Since the sexes were well separated by acetabulum measurements, this metric analysis lends itself well to sex estimation.

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TABLE 7. Results for the acetabulum method Acetabulum Method Left Right Male Mean 57.58 mm 57.69 mm Standard Deviation 2.99 3.18 Female Mean 51.41 mm 51.49 mm Standard Deviation 2.59 2.65 t 14.27 13.54 p <0.001 <0.001

Sectioning Point Left Right Sectioning Point 55.51 mm 55.62 mm Females Correctly Classified 92.4% 93.8% Females Classified as Male 7.6% 6.2% Males Correctly Classified 76.3% 76.9% Males Classified as Female 23.7% 23.1%

Sectioning points were calculated for each side using Klepinger and Giles

(1998). The sectioning point was 55.51 mm for the left and 55.62 mm for the right acetabula. Using the sectioning points, individuals were correctly classified in 81.7 percent of the sample (161 out of 197 individuals) using the left side, and 82.6 percent of the sample (161 out of 195 individuals) using the right side (Figures 40 and 41).

Individuals with acetabulum diameters falling below these sectioning points were categorized as female, while those with a maximum diameter higher than the sectioning point were categorized as male. Males were misclassified in 31 cases (23.7%) for the left and 30 cases (23.1%) for the right. Females were misclassified in 5 cases

(7.6%) for the left and 4 cases (6.2%) for the right. If an acetabulum diameter is larger than the sectioning point, there is a 95.2 to 96.2 percent chance of being correctly classified as male and a 3.8 to 4.8 percent chance of being incorrectly classified as

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Fig. 40. Maximum diameter of the left acetabulum. Sectioning point = 55.51 mm.

female. For acetabulum diameters falling below the sectioning points, there is a 66.3 to

67 percent chance of being correctly classified as female, and a 33 to 33.7 percent chance of being incorrectly classified as male.

When these sectioning points were tested on the individuals in the CSU Chico collection for whom sex was known, 100 percent of left (9 individuals) and 90 percent of right acetabula (9 out of 10 individuals) were sexed correctly. The individual sexed incorrectly had an acetabulum diameter of 55.49 mm, only 0.13 mm lower than the sectioning point. These sectioning points are accurate for this sample, which may indicate appropriateness for use with other samples.

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Fig. 41. Maximum diameter of the right acetabulum. Sectioning point = 55.62 mm.

Summary and Conclusions

All of the methods tested in this study demonstrate effectiveness as sex determination methods. The sex indicators recommended by Standards for Data

Collection all have a statistically significant relationship with biological sex, and sex determinations made using these methods were very accurate for females. Each of the aspects of the Bruzek method also showed a statistically significant relationship with biological sex, though in some cases many individuals were placed in the indeterminate category, making those traits questionable for use as sex indicators. The Bruzek method as a whole was very accurate for the cases that could be classified. There was also a

103 statistically significant difference between male and female acetabulum measurements. A test of the discriminant functions created with the Bass Donated Skeletal Collection was

90 to 100 percent accurate for individuals of known sex in the Human Identification

Laboratory at CSU Chico.

The revised Bruzek method presented here, in which sex estimations were based on the agreement of seven of the 11 Bruzek criteria, was able to correctly classify a larger percentage of individuals than the original method and placed fewer individuals in the indeterminate category. When the four criteria with the highest error rates were removed and determinations were made using the remaining seven, the number of individuals who could be correctly classified increased over the original method.

The next chapter will discuss reliability, accuracy, and the implications of these tests in the forensic context.

CHAPTER VI

DISCUSSION

Introduction

Assessment of reliability and accuracy is important for scientific studies.

Without an understanding of how reliably a sex estimation method can be applied, and how accurate that method is in making determinations, that method lacks validity. A method can be either reliable or accurate, neither reliable nor accurate, or both reliable and accurate. If a method is reliable but not accurate, or accurate but not reliable, it will not be useful for making sex determinations, since either multiple researchers will have discordant estimations or correct classification rates will be very low.

This chapter discusses the results presented in the previous two chapters. First, the observer error results are discussed, as well as what the results indicate regarding reliability. Next, the method results are discussed, including what they indicate about accuracy. Then the revised version of the Bruzek method as presented at the end of

Chapter Five is discussed, along with a discussion about which Bruzek criteria are the best indicators of sex for both the revised method and fragmentary remains. Finally, a discussion of the legal significance of this research is presented.

104 105

Reliability

When a method yields consistent results between observations and observers it is considered reliable. Reliability is established in this study in two ways. Observations were made twice by the author using the same skeletal materials and once by another observer. These observations were compared using Cohen’s kappa and paired t-tests in order to determine how consistent they were with one another for each method.

Intraobserver Reliability

Observations made by the author were highly concordant for all components of the methods recommended in Standards, as well as the sex determinations made with these methods. The kappa statistic determines how similar observations are when the same materials are used, and rates of concordance are statistically significant for this sample using the pelvic sex determination methods presented in Standards. Thus, the first and second observations are similar enough that we can say there are no substantive differences between them.

Use of the Bruzek method yielded consistent observations using both innominates for all but two components. Assessments of the composite arch and ischiopubic proportions were not significantly concordant between observations for either innominate. The ischiopubic pelvic complex, wherein the components of the inferior pelvis are combined with the ischiopubic proportion component, was also inconsistent for the left side, though the result did approach significance. For all other components and combined components of the Bruzek method, concordance was high and we can say they were assessed reliably between observations.

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The first and second measurements of the maximum diameter of the acetabulum were not statistically significant for either side. As the paired t-test measures the difference between related observations, it can be said that the 0.74 mm and 0.42 mm differences between these observations are not meaningful. The lack of a significant difference indicates that the acetabulum measurement can be taken reliably by the same individual with minimal measurement error.

Overall, these methods were reliable between the first and second observations conducted by the author. The second observations were conducted after data collection was completed at the University of Tennessee, Knoxville. This means that between the first and second observations, two hundred individuals (four hundred innominates) were assessed using all of these methods. It would be understandable if there is a difference between observations when experience of the observer has multiplied exponentially between the first and second observations. However, as only two components were significantly different, perhaps other explanations would be appropriate here. It is possible that the descriptions or figures used to guide scoring these criteria are ambiguous, precise locations of landmarks used to make estimations may be difficult to pinpoint, or these components may not be related to biological sex.

The description of the process of scoring the components, or the figure used to illustrate the male and female morphology, may explain the difference in observations. In the case of the composite arch, an innominate that should be scored as male can be misinterpreted depending on how much of the anterior chord of the auricular surface is considered. If the contour is followed only a few millimeters further than the highlighted

107 chord in the illustration, two separate arches can be observed, which would lead to scoring the component as female.

As far as ischiopubic proportions are concerned, the visual assessment is based on the same idea as the ischiopubic index (Bruzek 2002:162). While digital calipers were used for this component when proportions were not readily obvious, it is not always possible to locate the exact place in which the ilium, ischium, and pubis join in the acetabulum, which may be the reason for the discrepancy between observations.

The difference between the ischiopubic pelvic complex observations should be explained by the same phenomenon. Since all criteria of the inferior pelvis were in significant agreement, and the right ischiopubic proportion observation approaches significance (p =

0.063), it stands to reason that the ischiopubic pelvic complex would be significantly concordant on the right side while only approaching significance on the left side.

It is also possible that the composite arch and ischiopubic proportions do not have a relationship with biological sex. However, it appears that this is not the case. The results in Chapter Five, which are discussed below in the section on accuracy, suggest that there is a relationship between these criteria and biological sex. This could be the case for the composite arch, but it is probably not the explanation for the disparity between the first and second observations of ischiopubic proportions.

It is possible that all four explanations could work in accord and fit these results. Increased experience using a sex estimation method should make a difference in its application. Descriptions or illustrations used to aid determinations can also affect the reliability of a method. Difficulty in determining the precise location of a landmark can

108 make sex estimations inconsistent between observations. And it is possible that traits seen as sexually dimorphic for some populations may not be dimorphic in others.

Interobserver Reliability

Observations made by the author and another observer were highly concordant for the Standards methods and combined sex determinations, with two exceptions. The ventral aspect of the right innominate was not statistically significant, but approached significance (p = 0.063), and scores for the preauricular sulcus were not in agreement for either innominate. For the most part, the methods recommended by

Standards are reliable between observers for this study.

For the Bruzek method, only two components were concordant between observers, both of which were part of the greater sciatic notch criteria. Notch proportion scores were significantly concordant for the left side between observers, but did not approach significance for the right side. Greater sciatic notch contour was also highly concordant between observers for both innominates. Additionally, the combined greater sciatic notch criteria for the left side approached significance (p = 0.066). This is understandable, considering the significant agreement of two of the three criteria in this combination. Apart from these criteria, the Bruzek was not reliable for this study between observers.

Measurements of the maximum diameter of the acetabulum were significantly different between observers for both innominates. While the differences between mean diameters were relatively small, 0.91 mm for left acetabula and 1.22 mm for right acetabula, the differences were large enough to be significant. However, these differences are not likely to be meaningful, as they are still very small with respect to mean

109 acetabulum size, which was approximately 55 mm for the first observer and 54 mm for the second observer.

The Standards methods have been used by both observers on numerous occasions, which may explain the high rates of concordance for most of the components of these methods. The low rate of concordance for preauricular sulcus scores may be explained by differing perceptions of groove expression. For example, one observer may be more likely to score a preauricular sulcus as narrow and shallow when another observer may see a very small indication of activity in the preauricular area that is not large enough to classify as a sulcus and score it as absent.

The non-significant results between observers using the Bruzek method is not as likely explained by the increase in experience as the non-significant results in the intraobserver error portion of this study. The data of the second observer was compared to the author’s first observations in order to eliminate the possible bias created by different levels of experience using the method. However, the author was much more familiar with the Bruzek method through repeated readings of Bruzek (2002), which may have contributed to the differences between observers. And again there is a possibility that diagrams used to illustrate the observed criteria may have influenced each observer differently.

While the Bruzek method did not prove particularly reliable for this interobserver error study, most of the aspects of the methods recommended in Standards demonstrated a high degree of reliability. There were statistically significant differences between acetabulum measurements taken by both observers, but these differences are unlikely to be substantial, as they so small (0.91 to 1.22 mm). It is probable that the

110 acetabulum can be measured reliably by observers and can be used as a sex determination method.

Accuracy

A method that can correctly classify individuals can be considered accurate. A high percentage of correctly classified individuals indicates a more accurate method than one in which only a few individuals are placed within the correct category. Accuracy rates are determined in this study by comparison of correctly classified individuals versus incorrectly classified individuals (Tables 4 and 5).

The methods recommended by Standards for Data Collection (Buikstra and

Ubelaker 1994) performed very well for both sexes. The exceptions were females classifying as male for the preauricular sulcus criteria, and males classifying as probable female or ambiguous for the greater sciatic notch criteria. Studies using the preauricular sulcus and dorsal pitting have revealed that presence of this trait may be related to childbirth, but that not every woman will exhibit one regardless of parturition status

(Kelley, 1979; Cox and Scott, 1992). Since a preauricular sulcus will not be present in all females, the misclassification rate for females in this part of the study may simply be suggestive of this fact. Thus, the lack of a preauricular sulcus in a female should not be counted as a misclassification. Indeed, only the presence of a sulcus should be viewed as an indicator of sex, and even then incorrect sex estimations can be made, as some males will also exhibit a sulcus in the preauricular area. Dee (1981) discovered that as much as six percent of his sample of males possessed this trait, while 25 percent of his females did. The current research reveals a much higher prevalence of sulci in females (72.1%),

111 and a much lower percentage in males (2.3%). However, the individuals in Dee’s (1981) study were assessed using radiographs, while those in this research were analyzed after death by the unobstructed observation of the preauricular surface.

Walker (2005) discussed the range of variation in greater sciatic notch scores, particularly with respect to males. In Buikstra and Ubelaker (1994) a score of three is considered ambiguous, while a score of two is said to indicate a probable female. Walker suggests that a two may be more indicative of ambiguous morphology, and the current research validates this claim. A score of two was assigned to about a third of the males in this sample, and more males were assigned a score of three than any other score.

Together, 73.5 to 75.5 percent of males in this sample were scored as probable female and ambiguous for the sciatic notch if the Standards protocol is followed. While all females were assigned scores between one and three for the left side and one and two for the right side, males were assigned to every category. Reassignment of the score of two as ambiguous and three through five as male or probable male morphology would result in higher correct classification rates for males (62.1 to 62.9% versus 19.1 to 21.1% for the traditional scores), but lower correct classification rates for females (72.1% for each side versus 95.6 to 100%). However, this research lends support to Walker’s (2005) suggestion for reassignment of the greater sciatic notch scores as presented in Buikstra and Ubelaker (1994).

Sex determinations using all aspects of the methods recommended in

Standards correctly classified nearly all females in the sample (95.5 to 97%), but this was not the case for males (53 to 65.2%). However, only a small percentage of males were incorrectly classified as female (1.5 to 2.3%), meaning that the high rate of misclassified

112 individuals was due to ambiguous morphology. This was also the case for females, as all individuals for whom a correct classification was not made fell into the indeterminate category (3 to 4.5%). Elimination of those cases in which ambiguous morphologies were observed would increase the correct classification rate significantly. Aside from the exceptions listed above, the methods in Buikstra and Ubelaker (1994) have relatively low error rates (1.5 to 2.3% for the ventral aspect of the pubis, 1.5 to 3.1% for subpubic concavity, 0 to 3.1% for the ischiopubic ramus ridge, 0% for the female greater sciatic notch, and 2.3 to 4.6% for the male preauricular area), which explains why they have been in use for so long as the standard traits to make sex estimations.

As with the methods in Buikstra and Ubelaker (1994), the Bruzek (2002) method is significantly affected by ambiguous morphology. Much of the misclassification rate is due to the observation of ambiguous morphology rather than individuals being classified as the opposite sex. If individuals classified as indeterminate are removed from consideration, misclassification rates for the majority of individual

Bruzek criteria and combinations of criteria are quite low (4.5 to 33.8% for negative relief, 16.7 to 28.3% for relief border, 11.8 to 16.2% for the piriform tubercle, 0.8 to

10.3% for the preauricular area overall, 12.1 to 26.5% for greater sciatic notch proportion, 0 to 69.2% for greater sciatic notch symmetry, 7.4 to 22% for greater sciatic notch contour, 0 to 7.3% for the greater sciatic notch overall, 7.2 to 33.8% for the composite arch, 3.1 to 10.4% for eversion, 2.9 to 4.5% for morphology, 3.1 to 4.5% for robusticity, 1.5 to 3% for the inferior pelvis overall, and 1.5 to 11.7% for ischiopubic proportions).

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This research failed to replicate the results of Bruzek (2002) and Listi and

Bassett (2006) in terms of their high percentages of individuals that could be correctly classified. However, the individuals in this sample were born later than those in either of the other samples. The individuals analyzed for this research were born between 1906 and 1983, compared with 1820 through the first half of the twentieth century for the

Bruzek (2002) sample and 1822 to 1943 for the majority of the Listi and Bassett (2006) sample. This may account for some of the difference in classification accuracy.

The accuracy rate for innominates that could be classified using all 11 traits of the Bruzek method is extremely high (100%), as no cases were misclassified as the opposite sex for this sample. This was also the case for the sacroiliac pelvic complex sex determinations (100% correctly classified). The ischiopubic pelvic complex performed very well when indeterminate individuals are eliminated from consideration, as over 98 percent of the sample was correctly classified when determinations could be made. When all aspects of the Bruzek method, or either of the complexes of the Bruzek method, are in agreement, there is a very high likelihood that sex estimations will be accurate (98.4 to

100%).

The acetabulum method, as presented in Murphy (2000), also correctly classified a large percentage of individuals in this data set. Classification accuracy was higher for females, as acetabulum diameters tend to be smaller overall for females and more varied for males. This measurement corresponds to the use of the femoral head measurement as a sex estimation method, which has been tested and recommended by many researchers (Işcan and Ding, 1995; King et al., 1998; Asala, 2002; Bass, 2005;

Murphy, 2005). Since the femoral head fits into the acetabulum, and the femoral head has

114 long demonstrated usefulness in sex estimation, it stands to reason that maximum diameter of the acetabulum would make an effective sex estimation method. The accuracy rates for this research are 76.3 to 93.8 percent, which encompasses the 85.2 to

86.2 percent reported in Murphy (2000), as well as the accuracy rate reported for the same sample using femoral head diameter (80.9 to 82.4%) in Murphy (2005). As with any sex estimation method, but especially for males in this sample, the maximum diameter should be used in conjunction with other sexing criteria.

Each of the methods discussed here performed relatively well in correctly classifying sex, particularly when individuals with ambiguous morphology were removed. The methods recommended in Buikstra and Ubelaker (1994) demonstrated higher rates of reliability and accuracy than the other two methods, with the exception of the male greater sciatic notch. This study lends support to the continued use of the

Standards methods, particularly if Walker’s (2005) recommendations are taken into consideration.

The Revised Bruzek Method

Higher error rates make some criteria less accurate for sex estimation than others. When the four criteria with the highest error rates were removed, and determinations were made when all seven remaining criteria were in agreement, the number of correctly classified individuals was much higher than for the original Bruzek method (25 to 39.7%). Additionally, the number of individuals incorrectly classified as the opposite sex rose only slightly (1 versus zero for the full Bruzek method).

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Of the preauricular area criteria, border type was eliminated because much of the sample did not possess a preauricular sulcus (about 70%) and could not be scored for this criterion, and the error rate was high (16.7 to 28.3%). Greater sciatic notch proportion, with an error rate of 12.1 to 26.5 percent, was also eliminated. While greater sciatic notch symmetry was very accurate for males (97.7 to 100% correctly classified), it was not an adequate sex indicator for females, with an error rate of 63.2 to 69.2 percent.

The symmetry criterion appears to be most accurate only if the greater sciatic notch is symmetrical, as an asymmetrical notch was observed in 86 to 89.5 percent of the sample.

The last criterion eliminated was the composite arch, which had an error rate of 7.2 to

33.8 percent.

Two other criteria could have been eliminated for this analysis instead of those listed above. The error rate for negative relief was relatively low for males (4.5 to

9.1%), but was high for females (20.6 to 33.8%). This criterion was not eliminated because another criterion with a low error rate for males was already eliminated, and removing another low error rate for males would bias estimations against males. Greater sciatic notch contour had a low error rate for females (7.4 to 11.7%) but a high error rate for males (17.4 to 22%). This criterion was not eliminated because it was one of the two

Bruzek criteria which were highly concordant between observers in the interobserver error study.

In a test of the Bruzek method using a poorly preserved archaeological sample, Debono and Mafart (2006) recommended using border type, notch proportion, symmetry, and contour, as well as composite arch when estimating sex for fragmentary remains. Since preservation was worse for the inferior pelvis than the sacroiliac pelvic

116 complex, the inferior pelvis and ischiopubic proportions criteria were not effective for making sex estimations. However, that was not the case for this study. Error rates for eversion, morphology, robusticity, and ischiopubic proportions were low (1.5 to 10.4%), and the ischiopubic pelvic complex resulted in more correct classifications (70.3 to

75.8%) than the sacroiliac pelvic complex or the full Bruzek method (10.3 to 41.6% and

7.6 to 28.2%, respectively).

A revised version of the Bruzek method was created by making determinations based on the agreement of at least seven out of the eleven Bruzek criteria.

Classification accuracy is high for this revision of the Bruzek method (86.8 to 97.7%).

While more individuals were misclassified as the opposite sex for the revised method (0.8 to 4.4% versus 0%), there were significantly fewer individuals placed in the indeterminate category than for the original Bruzek method (2.3 to 13.2% versus 71.8 to

92.4%). This means that sex could be determined accurately for more individuals using the revised method than the original method, and that the number of individuals placed in the indeterminate category is much lower than for the full Bruzek method.

There must be room for normal human variation when using a sex estimation method. The full Bruzek method uses the agreement of all eleven criteria to make determinations, which resulted in a high percentage of individuals who could not be sexed. Even when the four traits with the highest error rates or those which did not perform well in the observer error studies were removed, the percentage of individuals in the indeterminate category was still high. However, if the method can be applied with more flexibility, more individuals can be correctly classified. The revised Bruzek method correctly classified 86.8 to 97.7 percent of individuals, indicating that an application of

117 this method that allows for normal human variation can lead to successful sex estimations.

Legal Significance

To be considered valid, a method must be tested and accepted by the scientific community. Prior to a landmark United States Supreme Court decision in 1993, the Frye rule governed the evidence entered into trials. The Frye rule, instated in 1923, required only that expert testimony given in court be accepted by the field in which the expert was testifying (Foster et al., 1993). The Federal Rules of Evidence, adopted in 1975, allowed scientists with specialized knowledge to testify, which eventually leads to a focus on the qualifications of the expert rather than the quality of the testimony to be presented

(Dirkmaat et al. 2008). In 1993, the Daubert v. Merrell Dow Pharmaceuticals ruling introduced more stringent requirements for the introduction of scientific evidence into the courtroom and effectively rejected the general acceptance criteria as the sole requirement for admissibility (Fienberg et al., 1995).

The Daubert decision states that evidence must be both relevant and reliable

(Berger, 2005). The requirement for relevance is met when an expert witness provides testimony which is appropriate to the case in question. The requirement for reliability is met when expert opinions are achieved through scientific means: testing, peer review, known error rates, and standardized operation of techniques used to reach conclusions.

Validation studies, such as the current research, have become important in testing the accuracy and reliability of previously published methods of identification as well as establishing known error rates for these methods.

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The results of the validation study discussed above reveal that rates of both reliability and accuracy are highest for the methods already widely in use for sex determinations in the legal context (Buikstra and Ubelaker, 1994). A change in the way greater sciatic notch scores are interpreted may be in order, however, since there was a high prevalence of males in the category traditionally interpreted as probable female. The

Bruzek (2002) method is less reliable and accurate than the Standards methods, although there may be potential for the use of this method when it is applied in a less constraining manner, as each of its criteria have demonstrated a statistical relationship with biological sex. Additionally, the instances in which sex determinations could not be made using this method limit its usefulness, lending further support to the development of a Bruzek-based method with a less strict application. The acetabulum method was reliable and accurate, indicating usefulness as a sex indicator. More research using this method with a modern sample is necessary, however, as the only other published test of this method utilized a prehistoric sample (Murphy, 2000). Until additional research is undertaken using the maximum diameter of the acetabulum as a sex indicator for modern individuals, its use in the forensic context is not recommended.

Summary and Conclusions

An understanding of the reliability and accuracy of any method of human identification is essential for both scientific and legal purposes. If repeated trials cannot produce the same results, and error rates are too high, producing low percentages of correctly classified individuals, a method will be inadequate in the legal or scientific context. On the other hand, if a method performs consistently through repeated trials and

119 can correctly classify a high percentage of individuals with a low rate of error, use of that method can be justified.

This research revealed that the methods recommended by Standards for Data

Collection (Buikstra and Ubelaker 1994) can consistently produce the same results when used by the same researcher or multiple researchers, and can correctly classify a large percentage of individuals with a low rate of misclassification. With a change in the scores assigned to the greater sciatic notch, as recommended by Walker (2005), sex determinations made using the pelvic methods in Standards would be even more accurate for males.

The Bruzek (2002) method performed consistently overall when used by the author, but the interobserver error rate was far from consistent for most aspects and combinations. Accuracy rates were very high for many individual aspects for both sexes, and in the case of the full Bruzek method and the sacroiliac pelvic complex, all individuals that could be assigned a sex were correctly classified. Misclassification rates were high, but when those of indeterminate sex are removed from consideration, the rate of incorrect classification is reduced significantly for most aspects and combinations.

The acetabulum method demonstrated consistency in the intraobserver error study, but did result in a statistically significant difference when two observers’ data were compared. However, the difference between the author’s and second observer’s measurements was small enough that it is not necessarily meaningful. When a sectioning point was used to determine sex, this method performed very well for females. Males were correctly classified less often because they demonstrated more variation in acetabulum diameter.

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When four criteria with high error rates were eliminated, the correct classification rates were higher than the original Bruzek method. A revised version of the

Bruzek method, wherein sex estimations were based on the agreement of seven or more of the 11 Bruzek (2002) criteria, performed very well in correctly classifying sex for this sample. While some individuals were misclassified using the revised Bruzek method, a less constricted use of the method resulted in a higher number of correctly classified individuals than was produced using the original method. Further research using this revision is recommended, as repeatability is essential for a successful sex determination method.

CHAPTER VII

CONCLUSION

The purpose of this research was to test the usefulness of methods of sex estimation of the pelvis in order to gain a better understanding of reliability and accuracy.

Validation studies like this one are important because it is necessary to know how methods of human identification perform on samples other than those used to create them as well as how they will perform when being used multiple times by the same researcher or by multiple researchers. It is also important that we understand how often an incorrect determination will be made using our methods.

Summary

The methods recommended in Standards for Data Collection (Buikstra and

Ubelaker 1994) were tested against the Bruzek (2002) method and the acetabulum method (Murphy 2000). While it is important to have a variety of sex estimation methods utilizing different elements of the skeleton at our disposal in the case of fragmentary remains, it is equally important that we utilize the methods and regions which perform with the highest rates of accuracy. Because the pelvis is a highly sexually dimorphic region of the skeleton, due in large part to obstetrical requirements, only pelvic methods were chosen for this research.

121 122

The skeletal collection curated in the CSU-Chico Human Identification

Laboratory at was used to perform intra- and interobserver error studies. Data was collected for the first time in May 2009 and a second time in September 2009. Individual aspects of these methods were compared, as well as determinations made using all of the criteria. Consistency of scoring was evaluated using the kappa statistic, which indicates the likelihood of chance agreement between two observations, and the paired t-test, which analyzes the means of two related metric variables to determine whether there is a significant difference between scores.

The intraobserver error study revealed a high degree of consistency between almost all observations. There was a high degree of concurrence between observations for all aspects of the Standards methods, as well as the sex determinations made using them together. This indicates that the Standards methods can be used reliably multiple times by the same researcher. Maximum diameter measurements of the acetabulum were also highly consistent between observations. The acetabulum measurements were not significantly different between observations, indicating that this method can be used reliably. Both of these methods demonstrate a high degree of consistency.

The only aspects which were not consistent between observations were parts of the Bruzek method. The composite arch and ischiopubic proportions were not consistent, and the ischiopubic pelvic complex, which combines all three inferior pelvis aspects and the ischiopubic proportions aspect, was consistent for the right side but only approached significance for the left side. The full Bruzek method, in which all criteria are combined to make sex determinations, was consistent for the right side, but only one innominate was sexed for both observations, while the rest were indeterminate. For the

123 left side, all innominates were indeterminate, so a kappa value could not be calculated.

While there was a high degree of consistency for the full method, the high percentage of individuals placed in the indeterminate category calls its effectiveness into question.

However, the high rate of consistency for individual aspects indicates that they can be applied reliably between observations.

The interobserver error study was conducted by comparing the author’s first set of observations with those of another graduate student. The author’s first observations were used in order to eliminate any bias created by different amounts of experience with the Bruzek and acetabulum methods. With the exception of the right ventral aspect of the pubis and the preauricular sulcus criteria for both sides, the observers achieved a high rate of consistency for the Standards methods. Sex determinations using the Standards methods were also very consistent between observers. There was a statistically significant difference between observers for the maximum diameter measurements of the acetabulum. However, the differences were very small and may have been due to measurement error. The Standards methods demonstrated reliability between observers, indicating that they can be applied consistently when used by different observers, but the acetabulum method requires further study.

The Bruzek method was consistent for only a few aspects. Greater sciatic notch proportion was consistent for the left side but not the right, and the notch contour aspect was significantly consistent for both sides. The overall greater sciatic notch combination approached significance on the left side. With the exception of these aspects, the Bruzek method was highly inconsistent between observers. This method did not

124 perform reliably between observers for most aspects and for all combinations of aspects, including the full method.

In addition to the intra- and interobserver error studies, each method was also compared with biological sex. The methods were used with a sample of 200 individuals from the Bass Donated Skeletal Collection at the University of Tennessee, Knoxville. All data was collected during a two-week period at the end of June and beginning of July

2009. First the individuals were scored using the Standards methods, then the Bruzek method was applied, and acetabulum measurements were recorded.

All aspects of the Standards methods were significantly related to biological sex, as were the sex determinations made using these methods. In most cases, the relationship between biological sex and expression of the aspects was very strong.

Additionally, correct classification rates were very high for these methods. The preauricular sulcus was the least accurate trait for females, while the greater sciatic notch was not very accurate for males. Females were sexed accurately more often than males for nearly all Standards aspects. The majority of individuals misclassified using the

Standards methods were placed in the indeterminate category rather than being incorrectly classified as the opposite sex.

The individual aspects and combinations of the Bruzek method were also statistically significantly related to biological sex. Correct classification rates for the

Bruzek aspects were lower in most cases for both males and females than for the

Standards methods. In most cases the misclassifications were due to individuals being placed in the indeterminate category, rather than being incorrectly placed in the opposite sex category. While the full Bruzek method was not able to sex the majority of

125 individuals, the individuals that could be sexed were sexed correctly in every case. This method was very accurate when determinations could be made, but the low number of individuals for whom determinations could be made suggests that the method may be too rigid in application.

The maximum diameter of the acetabulum was significantly different for males and females, indicating that it is useful as a sex indicator. Discriminant function analysis revealed that the acetabulum method separated males from females very well.

Sectioning points were calculated using the University of Tennessee, Knoxville, data and were applied to the individuals of known sex in the sample from California State

University, Chico. The sectioning points correctly classified a high percentage of females, but males exhibited more variation in maximum acetabular diameter. The maximum diameter of the acetabulum demonstrated promise as a good sex determination method.

Since the Bruzek method demonstrated a strong relationship with biological sex for all aspects and combinations, but often failed to provide a sex determination for the full method, a less strict application was adapted and tested with this sample. If at least seven of the 11 criteria were in agreement for an individual, a sex determination was made. While this alternative method did not meet the accuracy level of the original

Bruzek method when indeterminate individuals are included, the accuracy rate was very high, with very few individuals incorrectly classified as the opposite sex and a significant increase in the number of individuals who could be classified.

126

Limitations

Limitations of this study include the representativeness of the sample and researcher bias. While an attempt was made to obtain a sample that was representative of the population, sex was not known at the time of scoring. This resulted in a sample with almost twice as many males as females. There was a higher percentage of females in this sample than in the Bass Donated Skeletal Collection as a whole, but the percentage is still lower than for the population. This may have introduced some error into the study.

Additionally, the sample was not very diverse in terms of ancestry. The majority of individuals were white and representation of other ancestry groups was limited. It was not a goal of this study to evaluate differences in sexual dimorphism by ancestry, but it is possible that some or all of the morphology assessed could vary according to ancestry in addition to sex.

Researcher bias may have played a part in this study as well. While the attempt was made to limit bias, it is not always possible to assess a morphological trait without also observing other traits at the same time. For this reason the Standards methods were recorded for all individuals before collection of the Bruzek data. However, when examining an innominate, it is difficult to ignore everything but the trait being analyzed. It is possible that the assessment of some traits were influenced by the simultaneous observation of others.

Implications

There is a movement in the forensic sciences to standardize the procedures used in each discipline, so that error and bias are reduced (Committee on Identifying the

127

Needs of the Forensic Sciences Community et al., 2009). In order to standardize operating procedures, validation studies must be conducted and error rates known. This research sought to provide information on reliability and accuracy for the methods tested.

While the methods in Standards have been used for many years and are considered both accurate and reliable, it is important to continually reevaluate methods.

This movement toward standardization in the forensic sciences may lead to adoption of a different set of standards for development of a biological profile as more methods are reevaluated. The Bruzek and acetabulum methods, while newer, may prove reliable and accurate when more validation studies are done.

Conclusions

Future research should utilize other skeletal collections to further test the original Bruzek method as well as the revised method supplied here. While accuracy was high for individuals who could be sexed, this may not be the case for other studies. In fact, the results of this study may not be typical in terms of the number of indeterminate individuals.

More validation studies should also be performed with the acetabulum method with other skeletal collections, as this measurement appears to be effective for sex determination. The original method was tested on an archaeological population, so further studies should test it on modern populations. It seems likely that future research using this measurement will provide further evidence of its usefulness as a sex indicator.

Research must continue to test and retest methods in order to assure the most accurate and reliable sex determinations. This thesis provided validation for an already

128 respected and widely used group of sex determination methods, as well as examining two lesser-known methods with great potential.

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APPENDIX A

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT11‐03D 1 1 1 1 1 1 2 UT11‐03D 1 2 1 1 1 1 2 UT18‐03D 1 1 1 1 1 1 2 UT18‐03D 1 2 1 1 1 1 3 UT35‐04D 1 1 1 1 1 1 2 UT35‐04D 1 2 1 1 1 1 6 UT36‐04D 2 1 3 3 3 2 0 UT36‐04D 2 2 3 3 3 2 0 UT55‐04D 1 1 1 1 1 1 3 UT55‐04D 1 2 1 1 1 1 4 UT56‐04D 1 1 1 1 1 1 3 UT56‐04D 1 2 1 1 1 1 3 UT57‐04D 1 1 1 1 2 1 1 UT57‐04D 1 2 1 1 2 1 2 UT59‐04D 2 1 2 3 3 2 0 UT59‐04D 2 2 2 3 3 2 0 UT60‐04D 2 1 2 2 3 3 0 UT60‐04D 2 2 2 2 3 3 0 UT61‐04D 2 1 3 3 3 3 0 UT61‐04D 2 2 3 3 3 1 0 UT62‐04D 1 1 2 1 1 2 4 UT62‐04D 1 2 2 1 1 2 6 UT66‐04D 2 1 3 3 3 1 0 UT66‐04D 2 2 3 3 3 1 0 UT67‐04D 2 1 3 3 2 5 0 UT67‐04D 2 2 3 3 2 4 0 UT68‐04D 2 1 3 3 3 4 0 UT68‐04D 2 2 3 3 3 4 0 UT69‐04D 1 1 2 1 1 1 3 UT69‐04D 1 2 1 1 1 1 0 UT72‐04D 1 1 2 2 1 1 3 UT72‐04D 1 2 2 2 1 1 3 UT73‐04D 2 1 3 3 3 3 0 UT73‐04D 2 2 3 3 3 3 0 UT01‐05D 2 1 3 3 2 2 4 UT01‐05D 2 2 3 3 2 2 3 UT02‐05D 1 1 1 1 1 1 0 UT02‐05D 1 2 1 1 1 1 0 UT03‐05D 2 1 2 3 3 3 0 UT03‐05D 2 2 2 3 3 3 4 UT04‐05D 2 1 3 3 2 4 0

139 140

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT04‐05D 2 2 3 3 2 3 0 UT05‐05D 2 1 3 3 3 4 0 UT05‐05D 2 2 3 3 3 4 0 UT06‐05D 2 1 3 2 2 3 0 UT06‐05D 2 2 3 3 2 3 0 UT07‐05D 2 1 3 3 2 2 0 UT07‐05D 2 2 3 3 2 2 0 UT08‐05D 2 1 3 3 3 3 0 UT08‐05D 2 2 3 3 3 3 0 UT10‐05D 2 1 2 3 3 3 0 UT10‐05D 2 2 3 3 3 3 0 UT11‐05D 1 1 1 1 1 1 1 UT11‐05D 1 2 1 1 1 1 2 UT12‐05D 2 1 2 3 3 2 0 UT12‐05D 2 2 2 3 3 3 0 UT13‐05D 1 1 1 1 2 3 2 UT13‐05D 1 2 1 1 1 2 2 UT14‐05D 2 1 3 3 3 2 0 UT14‐05D 2 2 3 3 3 3 0 UT15‐05D 2 1 2 3 3 3 0 UT15‐05D 2 2 2 3 3 3 0 UT16‐05D 2 1 2 3 3 4 0 UT16‐05D 2 2 3 3 2 4 0 UT17‐05D 1 1 1 1 1 1 1 UT17‐05D 1 2 1 1 1 1 2 UT18‐05D 1 1 1 1 2 2 3 UT18‐05D 1 2 1 1 2 2 0 UT19‐05D 2 1 3 3 3 3 0 UT19‐05D 2 2 3 3 3 2 6 UT20‐05D 2 1 3 3 2 3 0 UT20‐05D 2 2 3 3 3 3 4 UT22‐05D 2 1 3 3 1 1 0 UT22‐05D 2 2 3 3 2 2 0 UT23‐05D 2 1 3 3 3 4 0 UT23‐05D 2 2 3 3 3 4 0 UT24‐05D 2 1 3 3 3 2 0 UT24‐05D 2 2 3 3 3 2 0 UT25‐05D 1 1 2 1 1 2 3 UT25‐05D 1 2 1 1 1 2 3 UT27‐05D 1 1 1 1 1 1 2 UT27‐05D 1 2 1 1 1 1 2 UT28‐05D 2 1 3 3 3 1 0 UT28‐05D 2 2 3 3 3 1 0 UT29‐05D 1 1 1 1 1 1 0 UT29‐05D 1 2 1 1 1 1 0 UT30‐05D 1 1 1 1 1 1 2 UT30‐05D 1 2 1 1 1 1 2

141

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT31‐05D 1 1 1 1 1 2 3 UT31‐05D 1 2 1 1 1 2 0 UT34‐05D 2 1 3 3 3 2 0 UT34‐05D 2 2 3 2 3 3 0 UT35‐05D 2 1 3 3 3 3 0 UT35‐05D 2 2 3 3 3 3 0 UT36‐05D 2 1 3 3 3 2 0 UT36‐05D 2 2 3 3 3 2 0 UT37‐05D 2 1 2 2 2 3 0 UT37‐05D 2 2 2 2 2 3 0 UT38‐05D 2 1 3 3 2 3 0 UT38‐05D 2 2 3 3 2 3 0 UT39‐05D 2 1 3 3 3 1 0 UT39‐05D 2 2 2 3 3 1 0 UT40‐05D 2 1 2 2 3 3 0 UT40‐05D 2 2 2 3 3 4 0 UT41‐05D 1 1 1 1 1 1 4 UT41‐05D 1 2 1 1 1 1 0 UT42‐05D 2 1 3 3 3 3 0 UT42‐05D 2 2 3 3 3 2 0 UT44‐05D 2 1 3 3 2 3 0 UT44‐05D 2 2 3 3 2 2 0 UT45‐05D 2 1 2 2 3 2 0 UT45‐05D 2 2 3 3 3 2 0 UT46‐05D 2 1 3 3 3 4 0 UT46‐05D 2 2 3 3 3 3 0 UT47‐05D 2 1 3 2 3 3 0 UT47‐05D 2 2 0 0 0 3 0 UT48‐05D 2 1 3 3 2 2 0 UT48‐05D 2 2 3 3 2 2 0 UT49‐05D 2 1 2 3 3 3 0 UT49‐05D 2 2 2 3 3 3 0 UT50‐05D 1 1 1 1 1 1 0 UT50‐05D 1 2 1 1 1 1 0 UT51‐05D 2 1 3 3 3 2 0 UT51‐05D 2 2 3 3 3 3 0 UT52‐05D 2 1 3 3 3 3 0 UT52‐05D 2 2 3 3 3 3 0 UT53‐05D 2 1 3 3 2 3 0 UT53‐05D 2 2 3 3 2 3 0 UT54‐05D 1 1 1 1 2 1 2 UT54‐05D 1 2 1 1 1 1 0 UT56‐05D 2 1 3 3 3 3 0 UT56‐05D 2 2 3 3 3 4 0 UT57‐05D 1 1 1 1 1 1 2 UT57‐05D 1 2 1 1 2 1 0 UT58‐05D 2 1 3 3 3 3 0

142

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT58‐05D 2 2 3 3 3 3 0 UT59‐05D 2 1 3 3 2 2 0 UT59‐05D 2 2 3 3 2 2 0 UT60‐05D 2 1 3 3 3 3 0 UT60‐05D 2 2 3 3 3 3 0 UT61‐05D 1 1 1 1 1 1 2 UT61‐05D 1 2 1 1 1 1 2 UT62‐05D 2 1 3 2 3 2 0 UT62‐05D 2 2 3 3 3 3 0 UT64‐05D 2 1 3 3 3 1 0 UT64‐05D 2 2 3 3 3 1 0 UT65‐05D 2 1 3 3 3 2 0 UT65‐05D 2 2 3 3 3 2 0 UT66‐05D 2 1 1 1 1 2 0 UT66‐05D 2 2 1 1 1 2 0 UT67‐05D 2 1 2 3 3 3 0 UT67‐05D 2 2 3 3 3 3 0 UT68‐05D 2 1 3 3 3 3 0 UT68‐05D 2 2 3 3 3 3 0 UT69‐05D 2 1 3 3 3 3 0 UT69‐05D 2 2 3 3 3 3 0 UT70‐05D 2 1 0 0 0 2 0 UT70‐05D 2 2 0 0 0 2 0 UT71‐05D 2 1 3 3 3 4 0 UT71‐05D 2 2 3 3 3 4 0 UT73‐05D 2 1 3 3 3 2 0 UT73‐05D 2 2 3 3 3 2 0 UT74‐05D 2 1 3 3 3 3 0 UT74‐05D 2 2 3 3 3 3 0 UT75‐05D 2 1 3 3 3 4 0 UT75‐05D 2 2 3 3 3 3 0 UT76‐05D 2 1 3 3 3 3 0 UT76‐05D 2 2 3 3 3 2 0 UT78‐05D 2 1 2 1 1 3 4 UT78‐05D 2 2 2 1 2 3 0 UT79‐05D 1 1 1 1 1 1 1 UT79‐05D 1 2 1 1 1 1 1 UT80‐05D 1 1 1 1 1 1 0 UT80‐05D 1 2 1 1 1 1 0 UT81‐05D 2 1 3 3 3 2 0 UT81‐05D 2 2 3 3 3 1 0 UT82‐05D 2 1 3 3 3 3 0 UT82‐05D 2 2 3 3 3 3 0 UT83‐05D 2 1 3 2 3 4 0 UT83‐05D 2 2 3 2 3 3 0 UT86‐05D 1 1 1 1 2 1 0 UT86‐05D 1 2 1 1 2 1 0

143

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT88‐05D 1 1 1 2 1 1 2 UT88‐05D 1 2 1 1 1 1 4 UT89‐05D 2 1 3 3 2 2 0 UT89‐05D 2 2 3 3 3 2 0 UT90‐05D 2 1 3 3 3 2 0 UT90‐05D 2 2 3 3 3 3 0 UT91‐05D 2 1 3 3 3 2 0 UT91‐05D 2 2 3 3 3 2 0 UT92‐05D 1 1 1 1 1 1 0 UT92‐05D 1 2 1 1 1 1 4 UT93‐05D 2 1 3 3 3 3 0 UT93‐05D 2 2 3 3 3 3 0 UT01‐06D 2 1 3 2 3 2 0 UT01‐06D 2 2 3 3 3 2 0 UT02‐06D 2 1 0 2 2 4 0 UT02‐06D 2 2 3 3 2 3 0 UT03‐06D 1 1 1 1 1 2 0 UT03‐06D 1 2 1 1 1 2 0 UT04‐06D 1 1 1 1 2 1 0 UT04‐06D 1 2 1 1 2 1 0 UT05‐06D 2 1 3 3 2 4 0 UT05‐06D 2 2 3 3 2 3 0 UT06‐06D 2 1 3 3 3 2 0 UT06‐06D 2 2 3 3 3 2 0 UT07‐06D 2 1 3 2 3 3 0 UT07‐06D 2 2 3 2 3 3 0 UT08‐06D 2 1 3 2 2 2 0 UT08‐06D 2 2 3 2 3 3 0 UT09‐06D 2 1 3 3 3 2 0 UT09‐06D 2 2 3 3 2 3 0 UT11‐06D 1 1 1 1 1 1 1 UT11‐06D 1 2 1 1 1 1 2 UT12‐06D 2 1 3 3 3 3 0 UT12‐06D 2 2 3 3 3 3 4 UT15‐06D 1 1 1 1 2 2 2 UT15‐06D 1 2 1 1 2 2 0 UT16‐06D 2 1 3 3 2 5 0 UT16‐06D 2 2 3 3 2 5 0 UT17‐06D 1 1 2 1 1 2 0 UT17‐06D 1 2 2 1 1 1 2 UT18‐06D 2 1 2 2 3 2 0 UT18‐06D 2 2 2 3 3 2 0 UT19‐06D 2 1 2 3 3 3 0 UT19‐06D 2 2 2 3 3 2 0 UT20‐06D 1 1 1 1 1 2 2 UT20‐06D 1 2 1 1 1 2 2 UT21‐06D 2 1 2 2 3 3 0 UT21‐06D 2 2 2 3 3 4 0

144

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT22‐06D 2 1 3 2 3 2 0 UT22‐06D 2 2 3 2 3 2 0 UT24‐06D 2 1 2 3 3 3 0 UT24‐06D 2 2 3 3 3 2 0 UT25‐06D 1 1 1 1 1 1 2 UT25‐06D 1 2 1 1 1 1 2 UT26‐06D 2 1 2 3 3 4 0 UT26‐06D 2 2 2 3 3 4 0 UT27‐06D 1 1 1 1 2 3 2 UT27‐06D 1 2 1 1 1 2 0 UT32‐06D 1 1 1 1 1 2 0 UT32‐06D 1 2 1 1 2 2 0 UT33‐06D 2 1 3 3 2 3 0 UT33‐06D 2 2 3 3 2 4 0 UT39‐06D 1 1 1 1 1 1 4 UT39‐06D 1 2 1 2 1 1 4 UT40‐06D 1 1 2 1 2 3 0 UT40‐06D 1 2 1 1 2 2 0 UT41‐06D 2 1 3 2 3 3 0 UT41‐06D 2 2 3 3 3 3 0 UT42‐06D 1 1 1 1 1 1 0 UT42‐06D 1 2 1 1 1 1 0 UT43‐06D 2 1 3 3 3 2 0 UT43‐06D 2 2 3 3 3 2 0 UT44‐06D 1 1 1 1 1 1 2 UT44‐06D 1 2 1 1 1 2 0 UT45‐06D 2 1 3 3 3 2 0 UT45‐06D 2 2 3 3 3 2 0 UT47‐06D 2 1 3 3 3 5 0 UT47‐06D 2 2 2 3 3 5 0 UT48‐06D 2 1 2 2 3 3 0 UT48‐06D 2 2 2 2 3 2 0 UT49‐06D 2 1 2 3 3 2 0 UT49‐06D 2 2 3 3 3 3 0 UT50‐06D 2 1 2 3 3 4 0 UT50‐06D 2 2 2 3 3 3 0 UT51‐06D 1 1 1 1 2 2 2 UT51‐06D 1 2 1 1 2 2 2 UT52‐06D 2 1 2 3 2 2 0 UT52‐06D 2 2 2 3 3 2 4 UT53‐06D 1 1 1 1 1 1 2 UT53‐06D 1 2 1 1 1 1 2 UT54‐06D 2 1 3 3 2 2 0 UT54‐06D 2 2 3 3 3 2 0 UT55‐06D 1 1 1 1 2 1 0 UT55‐06D 1 2 1 1 2 1 0 UT56‐06D 1 1 1 1 1 1 0

145

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT56‐06D 1 2 1 1 2 1 0 UT57‐06D 1 1 1 1 1 1 0 UT57‐06D 1 2 1 1 1 1 4 UT60‐06D 2 1 3 2 3 2 0 UT60‐06D 2 2 3 3 3 2 0 UT61‐06D 2 1 2 3 2 2 0 UT61‐06D 2 2 2 3 2 2 0 UT63‐06D 2 1 2 2 3 3 0 UT63‐06D 2 2 2 2 3 2 0 UT64‐06D 2 1 3 3 3 1 0 UT64‐06D 2 2 3 3 3 1 0 UT65‐06D 2 1 2 3 3 2 0 UT65‐06D 2 2 2 3 3 2 0 UT68‐06D 1 1 1 1 1 1 2 UT68‐06D 1 2 1 1 1 2 2 UT70‐06D 2 1 2 2 3 4 0 UT70‐06D 2 2 3 3 3 4 0 UT72‐06D 2 1 3 3 3 2 0 UT72‐06D 2 2 3 3 3 3 0 UT74‐06D 1 1 1 1 1 1 0 UT74‐06D 1 2 1 1 1 1 0 UT75‐06D 2 1 3 2 2 3 0 UT75‐06D 2 2 3 2 3 2 0 UT76‐06D 2 1 2 3 3 2 0 UT76‐06D 2 2 3 3 3 2 0 UT77‐06D 1 1 1 1 1 2 2 UT77‐06D 1 2 1 1 1 2 2 UT78‐06D 1 1 1 1 2 1 2 UT78‐06D 1 2 1 1 2 2 2 UT81‐06D 1 1 1 1 1 1 2 UT81‐06D 1 2 1 1 1 1 2 UT82‐06D 2 1 2 3 3 4 0 UT82‐06D 2 2 3 3 3 4 0 UT84‐06D 2 1 3 3 3 3 0 UT84‐06D 2 2 3 3 3 4 0 UT85‐06D 2 1 3 3 3 5 0 UT85‐06D 2 2 3 3 3 5 0 UT86‐06D 2 1 3 3 3 3 0 UT86‐06D 2 2 3 3 3 3 0 UT87‐06D 2 1 2 3 3 2 0 UT87‐06D 2 2 3 3 3 3 0 UT89‐06D 1 1 1 1 1 1 2 UT89‐06D 1 2 1 1 1 1 4 UT90‐06D 2 1 2 3 3 3 0 UT90‐06D 2 2 2 3 3 3 0 UT92‐06D 2 1 3 2 3 3 0 UT92‐06D 2 2 3 2 3 2 0 UT93‐06D 2 1 3 3 3 5 0

146

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT93‐06D 2 2 3 3 3 5 0 UT95‐06D 2 1 3 3 2 3 0 UT95‐06D 2 2 3 3 2 3 0 UT97‐06D 2 1 3 2 3 2 0 UT97‐06D 2 2 3 2 3 2 0 UT98‐06D 2 1 2 2 3 4 0 UT98‐06D 2 2 2 2 3 4 0 UT99‐06D 2 1 2 3 3 5 0 UT99‐06D 2 2 3 3 3 4 0 UT100‐06D 1 1 1 1 1 1 0 UT100‐06D 1 2 1 1 1 1 2 UT101‐06D 1 1 1 1 1 1 3 UT101‐06D 1 2 1 1 2 1 3 UT102‐06D! 2 1 1 1 3 3 4 UT102‐06D 2 2 2 1 3 3 4 UT104‐06D 2 1 3 2 3 2 0 UT104‐06D 2 2 3 3 3 2 0 UT105‐06D 2 1 3 3 3 5 0 UT105‐06D 2 2 3 3 3 5 0 UT106‐06D 2 1 1 1 1 2 0 UT106‐06D 2 2 1 1 1 2 0 UT107‐06D 1 1 1 1 1 1 4 UT107‐06D 1 2 1 1 1 1 0 UT03‐07D 1 1 2 1 2 1 3 UT03‐07D 1 2 2 1 2 1 1 UT05‐07D 1 1 1 1 1 1 2 UT05‐07D 1 2 0 0 2 1 0 UT07‐07D 1 1 1 1 1 2 4 UT07‐07D 1 2 1 1 1 1 4 UT08‐07D 1 1 1 1 1 1 4 UT08‐07D 1 2 1 1 1 1 4 UT11‐07D 2 1 2 3 3 3 0 UT11‐07D 2 2 0 0 0 4 0 UT12‐07D 2 1 2 3 3 2 0 UT12‐07D 2 2 2 3 3 3 0 UT15‐07D 1 1 1 1 1 1 4 UT15‐07D 1 2 1 1 1 1 0 UT19‐07D 2 1 3 3 2 4 0 UT19‐07D 2 2 3 3 3 4 0 UT20‐07D 2 1 3 3 2 3 0 UT20‐07D 2 2 3 3 3 3 0 UT26‐07D 2 1 3 3 3 3 0 UT26‐07D 2 2 3 3 3 3 0 UT27‐07D 1 1 1 1 2 1 1 UT27‐07D 1 2 1 1 2 1 2 UT29‐07D 2 1 2 3 3 3 0 UT29‐07D 2 2 2 3 3 3 0 UT31‐07D 1 1 1 1 2 2 0

147

Data: Standards for Data Collection Ventral Subpubic Ischiopubic Greater Preauricular Individual Sex Side Arc Concavity Ramus Ridge Sciatic Notch Sulcus UT31‐07D 1 2 1 1 2 2 4 UT33‐07D 1 1 3 3 2 2 0 UT33‐07D 1 2 3 3 2 2 0 UT35‐07D 1 1 1 1 1 1 2 UT35‐07D 1 2 1 1 1 1 2 UT39‐07D 2 1 3 3 3 3 0 UT39‐07D 2 2 3 3 3 4 0 UT41‐07D 1 1 1 1 1 1 1 UT41‐07D 1 2 1 1 1 1 1 UT43‐07D 2 1 3 3 3 4 0 UT43‐07D 2 2 3 3 3 4 0 UT44‐07D 2 1 2 3 3 4 0 UT44‐07D 2 2 2 3 3 4 0 UT47‐07D 2 1 3 3 3 3 0 UT47‐07D 2 2 3 3 3 3 0 UT57‐07D 2 1 2 3 3 3 0 UT57‐07D 2 2 2 3 3 4 0 UT60‐07D 2 1 3 3 3 2 0 UT60‐07D 2 2 3 3 3 3 0 UT61‐07D 1 1 1 2 1 2 1 UT61‐07D 1 2 1 1 1 1 2 UT78‐07D 1 1 1 1 1 2 2 UT78‐07D 1 2 1 1 1 2 2 UT79‐07D 2 1 3 3 2 3 0 UT79‐07D 2 2 3 3 2 2 0 UT81‐07D 2 1 3 3 3 3 0 UT81‐07D 2 2 3 3 3 4 0

148

Key ‐ Standards Data Sex 1 = Female 2 = Male Side 1 = Left 2 = Right Ventral Arc 0 = Unobservable 1 = Present 2 = Ambiguous 3 = Absent Subpubic Concavity 0 = Unobservable 1 = Present 2 = Ambiguous 3 = Absent Ischiopubic Ramus Ridge 0 = Unobservable 1 = Present 2 = Ambiguous 3 = Absent Greater Sciatic Notch 1 = Female 2 = Probable Female 3 = Ambiguous 4 = Probable Male 5 = Male 6 = Unobservable Preauricular Sulcus 0 = No Sulcus 1 = Wide, Deep Sulcus 2 = Wide, Shallow Sulcus 3 = Narrow, Deep Sulcus 4 = Narrow, Shallow Sulcus 6 = Unobservable

APPENDIX B

150

151

152

153

154

155

156

157

158

159

160

161

162

APPENDIX C

Data: Maximum Diameter of the Acetabulum Individual Sex Side Diameter Individual Sex Side Diameter UT11‐03D 1 1 53.81 UT05‐05D 2 2 64.57 UT11‐03D 1 2 55.4 UT06‐05D 2 1 52.27 UT18‐03D 1 1 49.04 UT06‐05D 2 2 52.35 UT18‐03D 1 2 47.79 UT07‐05D 2 1 57.74 UT35‐04D 1 1 57.06 UT07‐05D 2 2 56.92 UT35‐04D 1 2 55.06 UT08‐05D 2 1 65.35 UT36‐04D 2 1 56.12 UT08‐05D 2 2 65.9 UT36‐04D 2 2 56.11 UT10‐05D 2 1 57.95 UT55‐04D 1 1 48.95 UT10‐05D 2 2 56.83 UT55‐04D 1 2 49.4 UT11‐05D 1 1 49.37 UT56‐04D 1 1 48.79 UT11‐05D 1 2 50.26 UT56‐04D 1 2 49.27 UT12‐05D 2 1 59.85 UT57‐04D 1 1 53.08 UT12‐05D 2 2 57.54 UT57‐04D 1 2 999 UT13‐05D 1 1 48.25 UT59‐04D 2 1 53.58 UT13‐05D 1 2 48.84 UT59‐04D 2 2 50.25 UT14‐05D 2 1 51.49 UT60‐04D 2 1 57.24 UT14‐05D 2 2 50.48 UT60‐04D 2 2 56.64 UT15‐05D 2 1 59.39 UT61‐04D 2 1 54.08 UT15‐05D 2 2 60.5 UT61‐04D 2 2 53.91 UT16‐05D 2 1 57.63 UT62‐04D 1 1 48.39 UT16‐05D 2 2 56.13 UT62‐04D 1 2 49.76 UT17‐05D 1 1 49.34 UT66‐04D 2 1 60.24 UT17‐05D 1 2 50.16 UT66‐04D 2 2 61.37 UT18‐05D 1 1 52.96 UT67‐04D 2 1 50.81 UT18‐05D 1 2 53.3 UT67‐04D 2 2 52.6 UT19‐05D 2 1 58.59 UT68‐04D 2 1 53.91 UT19‐05D 2 2 57.47 UT68‐04D 2 2 55.09 UT20‐05D 2 1 55.03 UT69‐04D 1 1 51.33 UT20‐05D 2 2 52.77 UT69‐04D 1 2 51.41 UT22‐05D 2 1 53.84 UT72‐04D 1 1 49.79 UT22‐05D 2 2 54.34 UT72‐04D 1 2 48.98 UT23‐05D 2 1 60.37 UT73‐04D 2 1 56.52 UT23‐05D 2 2 60.66 UT73‐04D 2 2 58.88 UT24‐05D 2 1 55.79 UT01‐05D 2 1 58.48 UT24‐05D 2 2 56.22 UT01‐05D 2 2 57.78 UT25‐05D 1 1 50.51 UT02‐05D 1 1 50.09 UT25‐05D 1 2 51.35 UT02‐05D 1 2 50.05 UT27‐05D 1 1 48.86

164 165

Data: Maximum Diameter of the Acetabulum Individual Sex Side Diameter Individual Sex Side Diameter UT03‐05D 2 1 53.26 UT27‐05D 1 2 47.7 UT03‐05D 2 2 52.5 UT28‐05D 2 1 59.48 UT04‐05D 2 1 59.32 UT28‐05D 2 2 60.08 UT04‐05D 2 2 59.74 UT29‐05D 1 1 53.45 UT05‐05D 2 1 65.08 UT29‐05D 1 2 53.91 UT30‐05D 1 1 50.19 UT54‐05D 1 2 50.72 UT30‐05D 1 2 51.86 UT56‐05D 2 1 61.02 UT31‐05D 1 1 999 UT56‐05D 2 2 60.27 UT31‐05D 1 2 999 UT57‐05D 1 1 56.26 UT34‐05D 2 1 55.25 UT57‐05D 1 2 55.22 UT34‐05D 2 2 54.7 UT58‐05D 2 1 58.16 UT35‐05D 2 1 54.58 UT58‐05D 2 2 57.46 UT35‐05D 2 2 55.63 UT59‐05D 2 1 57.43 UT36‐05D 2 1 55.55 UT59‐05D 2 2 56.59 UT36‐05D 2 2 57.06 UT60‐05D 2 1 58.68 UT37‐05D 2 1 56.29 UT60‐05D 2 2 59.85 UT37‐05D 2 2 55.81 UT61‐05D 1 1 52.62 UT38‐05D 2 1 50.06 UT61‐05D 1 2 53.56 UT38‐05D 2 2 52.94 UT62‐05D 2 1 59.7 UT39‐05D 2 1 57.55 UT62‐05D 2 2 60.39 UT39‐05D 2 2 57.47 UT64‐05D 2 1 55.1 UT40‐05D 2 1 60.02 UT64‐05D 2 2 54.78 UT40‐05D 2 2 60.9 UT65‐05D 2 1 56.86 UT41‐05D 1 1 50.84 UT65‐05D 2 2 56.91 UT41‐05D 1 2 49.95 UT66‐05D 2 1 999 UT42‐05D 2 1 56.57 UT66‐05D 2 2 999 UT42‐05D 2 2 55.89 UT67‐05D 2 1 56.95 UT44‐05D 2 1 58.64 UT67‐05D 2 2 56.71 UT44‐05D 2 2 59.45 UT68‐05D 2 1 62.83 UT45‐05D 2 1 57.99 UT68‐05D 2 2 63.44 UT45‐05D 2 2 58.83 UT69‐05D 2 1 57.16 UT46‐05D 2 1 56.72 UT69‐05D 2 2 56.74 UT46‐05D 2 2 57.23 UT70‐05D 2 1 54.9 UT47‐05D 2 1 57.75 UT70‐05D 2 2 53.23 UT47‐05D 2 2 57.16 UT71‐05D 2 1 58.81 UT48‐05D 2 1 60.15 UT71‐05D 2 2 59.47 UT48‐05D 2 2 59.7 UT73‐05D 2 1 59.85 UT49‐05D 2 1 55.01 UT73‐05D 2 2 59.95 UT49‐05D 2 2 54.6 UT74‐05D 2 1 58.95 UT50‐05D 1 1 52.15 UT74‐05D 2 2 59.37 UT50‐05D 1 2 52.21 UT75‐05D 2 1 57.39 UT51‐05D 2 1 59.04 UT75‐05D 2 2 57.69 UT51‐05D 2 2 59.58 UT76‐05D 2 1 62.99

166

Data: Maximum Diameter of the Acetabulum Individual Sex Side Diameter Individual Sex Side Diameter UT52‐05D 2 1 59.78 UT76‐05D 2 2 63.86 UT52‐05D 2 2 59.1 UT78‐05D 2 1 52.37 UT53‐05D 2 1 54.34 UT78‐05D 2 2 52.91 UT53‐05D 2 2 54.31 UT79‐05D 1 1 999 UT54‐05D 1 1 51.4 UT79‐05D 1 2 51.34 UT80‐05D 1 1 50.07 UT12‐06D 2 2 56.99 UT80‐05D 1 2 49.98 UT15‐06D 1 1 52.02 UT81‐05D 2 1 56.41 UT15‐06D 1 2 54.4 UT81‐05D 2 2 57.37 UT16‐06D 2 1 59.53 UT82‐05D 2 1 55.47 UT16‐06D 2 2 60.23 UT82‐05D 2 2 55.71 UT17‐06D 1 1 57.15 UT83‐05D 2 1 54.17 UT17‐06D 1 2 57.9 UT83‐05D 2 2 53.2 UT18‐06D 2 1 57.19 UT86‐05D 1 1 49.03 UT18‐06D 2 2 57.73 UT86‐05D 1 2 999 UT19‐06D 2 1 62.9 UT88‐05D 1 1 54.26 UT19‐06D 2 2 65.38 UT88‐05D 1 2 55.16 UT20‐06D 1 1 55.17 UT89‐05D 2 1 58.77 UT20‐06D 1 2 56.04 UT89‐05D 2 2 59.31 UT21‐06D 2 1 57.06 UT90‐05D 2 1 59.69 UT21‐06D 2 2 57.45 UT90‐05D 2 2 60.09 UT22‐06D 2 1 55.17 UT91‐05D 2 1 62.52 UT22‐06D 2 2 57.3 UT91‐05D 2 2 65.04 UT24‐06D 2 1 57.53 UT92‐05D 1 1 50.71 UT24‐06D 2 2 57.03 UT92‐05D 1 2 51.63 UT25‐06D 1 1 54.96 UT93‐05D 2 1 58.07 UT25‐06D 1 2 54.61 UT93‐05D 2 2 56.86 UT26‐06D 2 1 63.02 UT01‐06D 2 1 57.16 UT26‐06D 2 2 62.27 UT01‐06D 2 2 57.42 UT27‐06D 1 1 50.25 UT02‐06D 2 1 52.44 UT27‐06D 1 2 50.7 UT02‐06D 2 2 52.52 UT32‐06D 1 1 50.6 UT03‐06D 1 1 49.52 UT32‐06D 1 2 51.02 UT03‐06D 1 2 48.98 UT33‐06D 2 1 55.63 UT04‐06D 1 1 46.98 UT33‐06D 2 2 55.74 UT04‐06D 1 2 46.88 UT39‐06D 1 1 50.52 UT05‐06D 2 1 57.71 UT39‐06D 1 2 49.43 UT05‐06D 2 2 57.84 UT40‐06D 1 1 57.22 UT06‐06D 2 1 55.15 UT40‐06D 1 2 57.63 UT06‐06D 2 2 54.97 UT41‐06D 2 1 60.92 UT07‐06D 2 1 65.28 UT41‐06D 2 2 61.9 UT07‐06D 2 2 63.4 UT42‐06D 1 1 53.71 UT08‐06D 2 1 61.99 UT42‐06D 1 2 53.96 UT08‐06D 2 2 64.35 UT43‐06D 2 1 56.92

167

Data: Maximum Diameter of the Acetabulum Individual Sex Side Diameter Individual Sex Side Diameter UT09‐06D 2 1 60.71 UT43‐06D 2 2 56.71 UT09‐06D 2 2 60.14 UT44‐06D 1 1 49.2 UT11‐06D 1 1 48 UT44‐06D 1 2 47.98 UT11‐06D 1 2 48.13 UT45‐06D 2 1 52.61 UT12‐06D 2 1 57.57 UT45‐06D 2 2 54.14 UT47‐06D 2 1 57.35 UT76‐06D 2 2 62.34 UT47‐06D 2 2 58.61 UT77‐06D 1 1 50.97 UT48‐06D 2 1 59.48 UT77‐06D 1 2 50.73 UT48‐06D 2 2 60.7 UT78‐06D 1 1 51.57 UT49‐06D 2 1 55.68 UT78‐06D 1 2 51.02 UT49‐06D 2 2 55.1 UT81‐06D 1 1 49.54 UT50‐06D 2 1 58.11 UT81‐06D 1 2 49.87 UT50‐06D 2 2 57.5 UT82‐06D 2 1 62.43 UT51‐06D 1 1 51.3 UT82‐06D 2 2 62.77 UT51‐06D 1 2 52.16 UT84‐06D 2 1 53.91 UT52‐06D 2 1 52.88 UT84‐06D 2 2 54.16 UT52‐06D 2 2 53.29 UT85‐06D 2 1 58.89 UT53‐06D 1 1 53.58 UT85‐06D 2 2 58.3 UT53‐06D 1 2 54.56 UT86‐06D 2 1 58.38 UT54‐06D 2 1 55.31 UT86‐06D 2 2 57.71 UT54‐06D 2 2 56.92 UT87‐06D 2 1 54.36 UT55‐06D 1 1 54.04 UT87‐06D 2 2 55.33 UT55‐06D 1 2 52.46 UT89‐06D 1 1 49.78 UT56‐06D 1 1 48.9 UT89‐06D 1 2 49.95 UT56‐06D 1 2 47.37 UT90‐06D 2 1 60.25 UT57‐06D 1 1 46.76 UT90‐06D 2 2 59.38 UT57‐06D 1 2 47.61 UT92‐06D 2 1 57.43 UT60‐06D 2 1 59.53 UT92‐06D 2 2 57.06 UT60‐06D 2 2 59.95 UT93‐06D 2 1 57.47 UT61‐06D 2 1 59.5 UT93‐06D 2 2 57.17 UT61‐06D 2 2 58.6 UT95‐06D 2 1 60.23 UT63‐06D 2 1 56.57 UT95‐06D 2 2 61.44 UT63‐06D 2 2 54.72 UT97‐06D 2 1 58.66 UT64‐06D 2 1 58 UT97‐06D 2 2 58.21 UT64‐06D 2 2 58.78 UT98‐06D 2 1 57.43 UT65‐06D 2 1 55.96 UT98‐06D 2 2 57.7 UT65‐06D 2 2 56.86 UT99‐06D 2 1 56.03 UT68‐06D 1 1 55.47 UT99‐06D 2 2 56.38 UT68‐06D 1 2 54.13 UT100‐06D 1 1 52.11 UT70‐06D 2 1 57.58 UT100‐06D 1 2 53.24 UT70‐06D 2 2 56.35 UT101‐06D 1 1 50.23 UT72‐06D 2 1 61.47 UT101‐06D 1 2 50.43 UT72‐06D 2 2 62.04 UT102‐06D 2 1 56.57

168

Data: Maximum Diameter of the Acetabulum Individual Sex Side Diameter Individual Sex Side Diameter UT74‐06D 1 1 52.06 UT102‐06D 2 2 55.91 UT74‐06D 1 2 52.15 UT104‐06D 2 1 58.64 UT75‐06D 2 1 56.64 UT104‐06D 2 2 59.71 UT75‐06D 2 2 56.71 UT105‐06D 2 1 55.61 UT76‐06D 2 1 61.45 UT105‐06D 2 2 55.34 UT106‐06D 2 1 53.97 UT31‐07D 1 1 53.42 UT106‐06D 2 2 53.43 UT31‐07D 1 2 54.34 UT107‐06D 1 1 57.58 UT33‐07D 1 1 51.2 UT107‐06D 1 2 56.36 UT33‐07D 1 2 50.54 UT03‐07D 1 1 54.08 UT35‐07D 1 1 51.53 UT03‐07D 1 2 52.14 UT35‐07D 1 2 50.5 UT05‐07D 1 1 50.43 UT39‐07D 2 1 59.11 UT05‐07D 1 2 49.41 UT39‐07D 2 2 59.63 UT07‐07D 1 1 53.24 UT41‐07D 1 1 48.65 UT07‐07D 1 2 52.72 UT41‐07D 1 2 48.1 UT08‐07D 1 1 48.79 UT43‐07D 2 1 60.38 UT08‐07D 1 2 49.09 UT43‐07D 2 2 61.17 UT11‐07D 2 1 56.52 UT44‐07D 2 1 57.9 UT11‐07D 2 2 999 UT44‐07D 2 2 58.75 UT12‐07D 2 1 54.59 UT47‐07D 2 1 63.57 UT12‐07D 2 2 54.19 UT47‐07D 2 2 63.74 UT15‐07D 1 1 48.15 UT57‐07D 2 1 54.89 UT15‐07D 1 2 49 UT57‐07D 2 2 54.3 UT19‐07D 2 1 56.62 UT60‐07D 2 1 57.37 UT19‐07D 2 2 55.92 UT60‐07D 2 2 58.62 UT20‐07D 2 1 50.75 UT61‐07D 1 1 51.58 UT20‐07D 2 2 51.51 UT61‐07D 1 2 52.76 UT26‐07D 2 1 60.41 UT78‐07D 1 1 50.04 UT26‐07D 2 2 60.53 UT78‐07D 1 2 49.76 UT27‐07D 1 1 52.46 UT79‐07D 2 1 61.02 UT27‐07D 1 2 54.3 UT79‐07D 2 2 59.89 UT29‐07D 2 1 58.81 UT81‐07D 2 1 56.44 UT29‐07D 2 2 58.15 UT81‐07D 2 2 56.69

Key ‐ Maximum Diameter of the Acetabulum Sex 1 = Female 2 = male Side 1 = Left 2 = Right Missing Data 999