In Exercises 8.49 and 8.50, we considered the study of one week of a 2006 college football season, during which the population of 53 FBS games had a mean spread (winning score minus losing score) of 16.189, with a standard deviation of 12.128. The sample of 4 games that were played that week in the next highest league, the FCS, had a mean of 8.75.

a. Calculate the appropriate measure of effect size for this sample.

b. Based on Cohen’s conventions, is this a small, medium, or large effect?

c. Why is it useful to have this information in addition to the results of a hypothesis test?