Interpreting Graphs of Developmental Data

Lab 1: Growth & Development Lab Name:______Score:______

In this lab, you will 1) gain experience in interpreting graphs of developmental data, 2) the opportunity of plot a velocity of curve for height and for weight, and 3) estimate one’s skeletal maturation by comparing hand and wrist X rays. Interpreting graphs of developmental data

Most development involves age-related changes that can be graphed over an age period. The horizontal axis represents the age or time and vertical axis the measurement being studied. In the graph, one can look across the horizontal axis and you can view how the measurement has changed over the age period or time. In graphing developmental data, one needs to keep in mind the type of measure and the age period. The lower numbers start at left on the horizontal axis and at the bottom on the vertical axis. The results are usually graphed as a line or bars. If you are graphing more than one variable, separate colored bars or different types of lines are used. Consider Table 1. It contains the mean height in centimeters of a group of children for every year staring with their 4th birthday and ending with their 9th. This would be what is called in chapter 1 of our Motor Development Text as “longitudinal data.” Enter the values and age categories of Table 1 then develop a line graph using your computer.

Table 1

Age 4 5 6 7 8 9 Height 107 114 122 127 131 137

Let assume that you have just plotted average height for a group of children that attends public schools in North America and a researcher in England sends you the average height measurements fro a group of England children. These average heights are in table 2. Plot the average on the same graph as before. Cut and paste the graph into the word document that includes your answers to the lab questions. Table 2

Age 4 5 6 7 8 9 Height 103 110 118 126 133 140

Consider table 3. It contains average scores in centimeters on the “sit and reach” flexibility test for four groups of boys. It also contains the average scores for four 1 groups of girls. Let say there is a strong cohort effect, such as the younger two groups’ have a teacher who led daily stretching exercises. Plot a graph by the various age groups for the sit and reach measure by gender using your software program. Cut and paste the graph into the word document that includes your answers to the lab questions.

Table 3

Age 15 16 17 18 Sit & Reach (B) 34.3 35.8 33.6 33.6 Sit & Reach (G) 39.1 41.9 38.1 37.9

Lab questions

1. Examine the first line (table 1) that you plotted on your graph. What does it tell you about height between 4 and 9 years of age in this group of children.

2. What does the graph tell you about the growth height of the England children? Compare the growth in height of the North American and England Children as shown by the graph (remember, these are not real data). Write out a year-by-year narrative that compares the two groups.

3. What does the bar graph tell you about age related trends in flexibility? About these trends in boys versus in girls?

4. Does there appear to be a cohort effect (rather than a developmental change) in the two youngest groups? Describe what you see the graph and explain your answer. Graphing a Velocity Curve

In the prior exercise you charted growth, we think of as a distance curve. A distance curve is where you plot the child’s height and weight at each birthday. From each graph we could see how far (distance) a child has grown at any age. If the line is flat, there is not growth. If the slope of the line is steep, the rate of growth or decline in growth is rapid. If we want to picture the rate of growth, we can take the change in growth from a distance curve and generate what is called a velocity curve, which plots speed or rate of growth against age. A velocity curve can be developed from any distance measure. The purpose of velocity curves is to identify any growth landmarks. Velocity curves will include peaks and valleys. A velocity curve enables us to identify the age at which the growth was the fastest (age of peak velocity). It is interesting to compare age at peak velocity between genders and other variables for various growth measures.

2 Table 4 gives the height (in cm) attained by a boy and a girl on each of their birthdays from 4 to 20 years of age. Plot a distance curve for the child your professor assigns, making sure height is on the vertical axis and age is on the horizontal axis. Graph these data with a computer software program such as Excel. Cut and paste this graph into your work document that includes your written answers to the lab questions associated to graphing a velocity curve. Table 4

Age 4 5 6 7 8 9 10 11 12 13 14

B 105 111 126 130 130 137 143 148 156 164 171

G 98 104 111 117 123 128 133 138 145 152 156 Age 15 16 17 18 19 20 B 176 179 181 182 183 183 G 157 158 158 159 159 159

For these height data, complete the table 5, showing the change in height from one birthday to the next. When you have completed this table, plot a velocity curve. The common practice is to plot the change at the midpoint of the age period. In this case, you would plot the change from 4 to 5 (6 cm) at 4.5 years. Cut and paste the graph into the word document that includes your answers to the lab questions.

Table 5

4-5 5-6 6-7 7-8 8-9 9-10 10 11- 12- 13- 14- Interva -11 12 13 14 15 l Change

Interva 15- 16- 17- 18- 19- l 16 17 18 19 20 Change

Lab Questions

5. Look at your height distance curve. Can you see points of apparent transition from a period of faster growth (where the curve is steep) to a period of slower growth (where the curve goes up gradually)? What about transitions from a period of a slower growth to a period of faster growth or inflection 3 point? What are the ages of the child at the inflection points you identified? Developmentalists often use the term “age at takeoff” for the age at an inflection point marks a transition from slower to faster growth. What would the age at takeoff for any such inflection point for this child? 6. Look at your velocity curve. Is the rate of growth faster at younger ages or older ages? What is the basis for your answer? Do you see peaks and valleys in your velocity curve? At what ages? What do the velocity curves show when then distance curve plateau? 7. Look at the most pronounced peaks on your velocity curves. Look at the distance curves around the age corresponding to the peak height velocity and the peak weight velocity. What is the characteristic of the distance curves at these points? Estimating Skeletal Age

Physiological maturation is more difficult to measure than physical growth. It is harder to see the biochemical and structural changes of the body’s cells, organs, and systems. Error is often about physiological maturation solely on the basis of age or size. Skeletal maturation is a component of physiological maturation that can be used at any time in the growth period to estimate overall physiological maturation. The most common sites are the wrist and hand. Wrist and hand is used because we have established standards published (A Radiographic Standard of Reference for the Growing Hand) by S.I. Pyle that contains many X rays for various ages throughout a growth period. When you compare the X rays look at the roundish of the carpal bones of the wrist, the epiphyseal growth plates of the long bones of the hand and fingers, and the epiphyseal growth plates of the forearm bones to determine one’s physiological maturation.

The professor will assign you to study the X ray of the hand and wrist in either example A or example B. Compare the X ray to those in your textbook (Figures 6-25 and 6-27, pages 163-4). Note the number of wrist bones (carpals), ossified, the extent of their ossification, and the extent of the ossification at the epiphyseal growth plates located at the end of the long bones of the hand(metacarpals and phalanges) and forearm (radius and ulna). The extent of ossification at an epiphyseal growth plate is typically seen by how complete the end of the bone is ossified. The epiphysis seen as being larger and as having more of an eventual adult shape is considered to be more mature. Example A Example B

4 As you compare the X ray in this lab with the textbook’s X ray, record the results of your comparison in Table 6. Enter “M” if the number of ossification centers is more than the standard, “L” if less, and “S” if the same.

Table 7

Criteria Textbook Figure 6-25 Textbook Figure 6-27 Number of Wristbones (carpal) ossified Extent of wristbone ossification Growth plate at distal end of radius Growth plate at distal end of ulna Growth plates at distal end of metacarpal (hand) Growth plates of the phalanges (fingers)

Lab Questions:

8. From your assessment as recorded in Table 6, is the child whose X ray your evaluated more or less physiologically mature than pictured in textbook figure 6-25? Than pictured in textbook figure 6-27?

5 9. Figure 6-25 in the textbook shows the skeletal age for a boy to be 36 months of age. Figure 6-26 in the textbook shows the skeletal age for a boy to be 60 months of age. Figure 6-27 in the textbook show the skeletal age for a boy to be 14 years old. Based on your comparison you did and reported in table 7 and assuming that your X ray is for a boy, what would you estimate the skeletal age of your child to be? On what do you base your estimate? 10. Assuming that the age of your boy’s X ray is 78 months. Compare this to the skeletal age you estimated in answer 9. Is your child an early maturer, average, or late maturer? On what do you base your answer?