\1. Of TECHpO JUN 22 1960 LIB RAR'( STUDY OF POPULATION SAMPLING PROCEDURES and DEVELOPMENT OF PROPORTIONATE-STRATIFIED AREA RANDOM SAMPLE within CAMBRIDGE, MASSACHUSETTS by Edmond Patrick Coady, Jr. SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY 1960 Signature redacted Signature of Author.............. ... a..r reda .... Lchpo' of Industr7P7~ianagement redacted Certifiedb .. Signature. ........ o....... Faculty A visor of The Thesis Professor Philip Franklin Secretary of the Faculty Massachusetts Institute of Technology Cambridge 39, Massachusetts Dear Professor Franklin: In accordance with the requirements for graduation, I herewith submit a thesis entitled "STUDY OF POPULATION SAMPLING PROCEDURES AND DEVELOPMENT OF A PROPORTIONATE- STRATIFIED AREA RANDOM SAMPLE within CAMBRIDGE, MASSACHUSETTS" in partial fulfillment of the requirements for the Degree of Bachelor of Science. I want especially to thank my advisor for his patience and direction. In addition, recognition should be given to my typist, Mrs. Rundlett, and the staff at the Cambridge City Planning Board. Sincerely yours, E. Patrick Coady ABSTRACT STUDY OF POPULATION SAMPLING PROCEDURES and DEVELOPMENT OF A PROPORTIONATE-STRATIFIED AREA SAMPLE within CAMBRIDGE, MASSACHUSETTS Edmond Patrick Coady, Jr. Submitted to the School of Industrial Management on May 23, 1960, in partial fulfillment of the require- ments for the degree of Bachelor of Science. The problem in this paper is twofold. First to study sampling methodology and theory, and secondly, to select a random population sample from Cambridge, Massachusetts. The Cambridge City Planning Board in 1954 adopted the Neighbor- hood theory of districting; the city was divided into thirteen areas or strata such that each area had internal social and economic homo- geity. These thirteen neighborhoods were then assumed to stratify the city into areas of equal income. The elementary sampling unit chosen was the dwelling unit. A four step procedure was employed to reach the elementary sampling unit; division of the city into thirteen districts, differentiation of the commercial areas from the residential areas, a sample of blocks was drawn from residential areas, and dwelling units chosen from the blocks. The five major conclusions: 1. The Neighborhood is a good stratification when it conforms to Perry's definition of the ideal Neighborhood. 2. Sampling by mapping techniques is easily under- stood, inexpensive, and not extremely time consuming. 3. The sample designer should not overlook the logistical problem of ob- taining maps, Census data, and directories. 4. A small sample size is susceptible to bias, especially with sub-strata. 5. Every stage of a sample design is interdependently related to the other stages; therefore the sample designer should be aware of the pro- blems that exist from the planning through the execution of the plan. Thesis Advisor: Professor Richard B. Maffei Title: Professor of Industrial Management Letter of Transmittal.. Abstract.................................................... 1 Chapter I. Introduction........................................ Problem and Its Setting............................1 Purpose of Study..................................2 Research Methods................................... 3 Major Conclusions...................................4 II. Survey of Sampling Methods and Resources............... 6 Introduction......................................6 What Sampling Is................................... 7 Types of Sampling Designs..........................9 Information Sources of Population Listings..........14 Suzmmary............................................15 III. Area Sampling & Definitions..........................18 Introduction.......................................18 Proportionate-Stratified Area Sample................19 Division of City Into Sub-Areas.....................19 The Neighborhood Theory...........................21 Advantages of An Area Sampling Plan................23 Definitions........................................25 Summary............................................28 IV. Sampling Procedures and Examples.......................31 Introduction.......................................31 Procedure for Drawing a Sample....................31 A Caveat...........................................42 Sources of Error..................................43 Summary............................................44 V. Conclusion...........................................47 Major Conclusions...........................47 Areas for Further Study...........................49 Appendix A Sources of Population Lists and Information......52 Appendix B Cambridge: The Thirteen Neighborhoods...........57 TABLE OF CONTENTS (Continued) Appendix C Tables: Census Data.............................64 Table 1 General Characteristics................. Table 2 Census Data by Neighborhoods........... Table 3 Census Data: Neighborhoods 1 & 11. Appendix D Maps of Cambridge................................68 Map 1 Neighborhood & Census Tracts............. Map 2 Residential Areas...................... Map 3 Detail: Neighborhoods 1 & 2............. Map 4 Detail: Neighborhood 11................ Appendix E Different Districting Systems in Cambridge......... 74 Appendix F Examples of Instructions.......................... 78 Sheet 1 Selection of Structures Within Block.... Sheet 2 Apartments: Selection of Dwelling Unit.. Sheet 3 Neighborhood 1, Block 25, Selection of Building Structures................. Sheet 4 Neighborhoods 2 & 11: Calculations in Choosing S"mple Blocks................ Bibliography................................................. 84 CHAPTER 1 INTRODUCTION Problem and Its Setting Within the field of Industrial Management there are many times when one must deal with sampling techniques. This paper touches closest to the area of market research and opinion polls. Most often the person interested in conducting some inquiry into the population does not want to devote a great deal of time in the design of the sampling pln. He usually will want to concentrate on the formulation of the questionnaire and the tabulation of the results. Another problem that is often overlooked is knowing what studies relevant to one's question have been done, what directories, maps, and population data are available and how they can be obtained. The body of the thesis is divided into three sections. First there is a survey of all the different facets of executing a sampling plan with some attention to general theory and methods. Different types of sampling plans and the resources necessary to use them are outlined with special attention to selection of a sampling design and the procedure for drawing a sample with this design. The second section deals with the advantages and disadvantages of the sample design chosen, which was a stratified area or geographical design employing city maps. The third section discusses the details of 2. actually drawing a sample using sampling and problems that one might run into. Purpose of Study The purpose of this thesis is to introduce sampling theory and methods to a person who has had no formal training in this field. The presentation is geared to provide a quick survey of the different facets of sampling and serves as an introduction to the background of sampling'. The thesis was designed with the idea that it would be used by some person interested in sampling a human population for a market research study, social psychology inquiries or any similar survey concerned with population means or averages. A specific procedure ,,as developed for the city of Cambridge, Massachusetts. By using and extending the procedures outlined in this thesis the prospective sampler can perform his survey without expending a great deal of time in preliminary research in order to familiarize himself with the problems involved in sampling. A word of caution should be inserted here. This paper does not cover all details of sampling and the prospective user should examine what facets are included and what ones are excluded. The second chapter gives two excellent references where one can obtain further detail. Research Methods The types of procedure chosen to draw a population cross section from Cambridge, Massachusetts was a proportionate- stratified area sampling plan. An area sample means that the sample will be selected with the aid of maps. The city will be divided along economic and social lines into strata and samples will be drawn from these strata in proportion to the total human population in the strata. In 1953 the Cambridge City Planning Board adopted a districting plan of the city based on Clarence A. Perry's Neighborhood theory. The essentials of the Neighborhood theory are to divide the city into sections that are self sufficient as to elementary schools, grocery stores and commercial services. The center of gravity of the neigh- borhood is the elementary school. Secondly, the neighborhood is to be bounded by main traffic arteries or natural physical barriers. This will create a homogeneous population that is clearly defined by boundaries easily recognizable by field workers. In the light of these advantages thirteen neighborhoods were chosen as strata or sub- areas of the city. The next step was to use planning board maps .and Sanborn Insurance Maps to separate the commercial from residential areas. I numbered all the blocks that were classified as residential, and by application of random selection