Question: Stephen Schmidt (1994) conducted a series of experiments examining the effects of humor on memory. He collected a set of humorous sentences and then modified each one to produce a non-humorous version of the same sentence. The humorous sentences were then presented to one group of 16 participants and then non-humorous sentences were presented to another group of 16. Each group was then given a test to determine how many sentences they could recall. Data similar to those obtained by Schmidt are shown in the following table: (10 pts)

a. Do the data provide enough evidence to conclude that humor has a significant effect on memory?

(1) Use a one-tailed test at the .05 level of significance.

(2) Use a two-tailed test at the .05 level of significance.

b. Calculate Cohen’s d to evaluate the size of the effect.

c. Calculate the percentage of variance explained by the treatment, r², another index to measure effect size.