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 participants and the non-humorous sentences were presented to another group. 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.

Number of sentences recalled:

Humorous Non-humorous

4 5 2 4 5 2 4 2

6 7 6 6 2 3 1 5

2 5 4 3 3 2 3 3

3 3 5 3 4 1 5 3

a. Do the data provide enough evidence to conclude that humor has a significant effect on memory? 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, r 2, to measure effect size.