1. Describe what is measured by the estimated standard error in the bottom of the independent-measures t statistics.
2. Do you view a chocolate bar as delicious or as fattening? Your attitude may depend on your gender. In a study of American college students, Rozin, Bauer, and Catanese (2003) examined the importance of food as a source of pleasure versus concerns about food associated with weight gain and health. The following results are similar to those obtained in the study.
The scores are a measure of concern about the negative aspects of eating.
Males
N = 6
M = 31
SS = 490
Females
N = 9
M = 45
SS = 680
a. Based on these results, is there a significant difference between the attitudes for males and for females? Use a two tailed test with alpha = .05.
b. Compute r2, the percentage of variance accounted for by the gender difference, to measure effect size for this study.
3. Steven Schmidt (1994) conducted a series of experiments examining the effects of humor on memory. In one study, participants were given a mix of humorous and nonhumorous sentences and significantly more humorous sentences were recalled. However, Schmidt argued that the humorous sentences were not necessarily easier to remember, they were simply preferred when participants had a choice between the two types of sentences. To test this argument, he switched to an independent-measures design in which one group got a set of exclusively humorous sentences and another group got a set of exclusively nonhumorous sentences. The following data are similar to the results from the independent-measures study.
Humorous Sentences
4 5 2 4
6 7 6 6
2 5 4 3
3 3 5 3
Nonhumorous Sentences
6 3 5 3
3 4 2 6
4 3 4 4
5 2 6 4
Do the results indicate a significant difference in the recall of humorous verus nonhumorous sentences? Use a two-tailed test with alpha = .05.
4. A researcher conducts an independent-measures research study and obtains t = 2.070 with df = 28.
a. How many individuals participated in the entire research study?
b. Using a two-tailed test with alpha = .05, is there a significant difference between the two treatment conditions?
c. Compute r2 to measure the percentage of variance accounted for by the treatment effect.