12.7 PA All applicants for municipal jobs in Pearson, Ontario, are given an aptitude test, but the test has never been evaluated to see whether test scores are in any way related to job performance.

The following table reports aptitude test scores and job performance ratings for a random sample of 75 city employees.

Efficiency Ratings Test Scores Low Moderate High Totals Low 11 6 7 24 Moderate 9 10 9 28 High 5 9 9 23 Totals 25 25 25 75

a. Are these two variables associated? Compute gamma, then describe the strength and direction of the relationship in a sentence or two.

b. Is gamma statistically significant?

c. Should the aptitude test continue to be administered?
Why or why not?