Question: A researcher is comparing the effectiveness of two sets of instructions for assembling a child’s bike. A sample of eight fathers is obtained. Half of the fathers are given one set of instructions and the other half receives the second set. The researcher measures how much time is needed for each father to assemble the bike. The scores are the number of minutes needed by each participant.

Instruction Set I Instruction Set II

8 14

4 10

8 6

4 10

a. Is there a significant difference in time for the two sets of instructions? Use a two-tailed test at the .05 level of significance.

b. Calculate the estimated Cohen’s d and r 2 to b measure effect size for this study.