An educational psychologist studies the effect of frequenttesting on retention of class material. In one section of anintroductory course, students are given quizzes each week. A secondsection of the same course receives only two tests during thesemester. At the end of the semester, both sections receive thesame final exam, and the scores are summarized below.
Frequent Quizzes Two Exams
n=20 n=20
M=73 M=68
a. If the first sample variance is s2 = 38 and the second samplehas s2 = 42, do the data indicate that testing frequency has asignificant effect on performance? Use a two-tailed test at the .05level of significance. (Note: because the two sample are the samesize, the pooled variance is simply the average of the two samplevariances.)
b. If the first sample variance is s2 = 84 and the second samplehas s2= 96, do the data indicate that testing frequency has asignificant effect? Again, use a two-tailed test with x = .05.
c. Describe how the size of the variance effects the outcome ofthe hypothesis test.
