# Understanding Statistics in the Behavioral Sciences

A graduate student in developmental psychology believes there may be a relationship between birth weight and subsequent IQ. She randomly samples seven psychology majors at her university and gives them an IQ test. Next she obtains the weight at birth of the seven majors from the appropriate hospitals

(after obtaining permission from the students, of course). The data are shown in the following table.

Birth Weight

Student

(lbs)

IQ

1

5.8

122

2

6.5

120

3

8.0

129

4

5.9

112

5

8.5

127

6

7.2

116

7

9.0

130

a. Construct a scatter plot of the data, plotting birth weight on the X axis and IQ on the Y axis. Does the relationship appear to be linear?

b. Assume the relationship is linear and compute the value of Pearson r.