4. An educational psychologist studies the effect of frequent testing on retention of class material. In one section of an introductory course, students are given quizzes each week. A second section of the same course receives only two tests during the semester. At the end of the semester, both sections take the same final examination. The summarized scores below frequent quizzesn=20, M=73, two exams- n=20;M=68.
a. If the sample variance is s2=38 and second has s2=42, do the data indicate that testing frequency has siggnificant effect on performance? Use a two tailed test at the .05 level of signifficance. (note because the two samples are the same size, the pooled variance is simply the average of the two sample variances.)
b. If the first sample variance is s2=84 and the second sample has s2=96, to tge data indicate that testing has signifficant effect? Again use a two tailed test with Alpha=.05.
c. Describe how the size of the variance effects the outcome of the hypothesis testing?
