Question: 1. List the four topics that determine the power of an experiment. [If you can recall them without looking at the text, you know that you have been reading actively (and effectively).]

2. What is the effect of set (previous experience) on problem solving? In a classic experiment by Birch and Rabinowitz (1951), the problem was to tie together two strings (A and B in the illustration) that were suspended from the ceiling. The solution to the problem is to tie a weight to string A, swing it out, and then catch it on the return. The researcher supplied the weight (an electrical light switch) under one of two conditions. In one condition, participants had wired the switch into an electrical circuit and used it to turn on a light. In the other condition, participants had no experience with the switch. Does education (wiring experience) have an effect on the time required to solve the problem? State the null hypothesis, analyze the data in the accompanying table with a t test and an effect size index, and write a conclusion.

             Wired the switch into circuit                 No previous experience with switch

X¯                7.40 minutes                                                5.05 miniutes

s^{^}                2.13 minutes                                                2.31 miniutes

N                       20                                                               20