Question: A researcher is interested in the possible relationship between two of the subsets on the WAIS (Wechsler Adult Intelligence Scale). A random sample of eight Army recruits is selected; they are given both the Vocabulary subtest and the Digit Span (a test of short-term memory) subtest. Their scores are as follows:

a. Plot the data and describe the scatterplot.

b. Compute the correlation between the two sets of subtest scores, and test for its significance.

c. Construct a regression equation for predicting Vocabulary scores knowing Digit Span scores.

d. If one of the subjects receives a score of 11 on the Digit Span subtest, what is your best estimate of the subtest score that person will receive on the Vocabulary subtest?