A researcher wants to know whether an educational video about genetics is effective. This researcher created a quiz assessing knowledge about genetics. She recruited 6 undergraduates and gave them the quiz as a pre-test. Then they watched the educational video, and took the test a second time.

StudentPre-testPost-test

Anne27

Bob45

Cathy57

Dave78

Emma29

Fred46

1. Compute the mean difference score.
2. Compute the SS (sums of squares) of the difference scores.
3. Compute the sample variance (of the difference scores).
4. Compute the estimated standard error of the difference scores.
5. Compute the t-test for repeated measures.
6. Is this t-test significant, if you assume an alpha of .05 and a two-tailed test?
7. Compute estimated Cohen's D for this test:
8. Compute the r-square estimate of the effect size for this test: