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 nonhumorous version of the same sentence. The humorous sentences were then presented to one group of participants and the nonhumorous 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 Nonhumorous

Sentences Sentences____

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, r², to measure effect size.