A psychology student was interested in the effect of group size on the likelihood of joining an informal group. On one part of the campus, he had a group of two people looking intently up into a tree. On a distant part of the campus, a group of five stood looking up into a tree. Single passersby were classified as joiners or nonjoiners depending on whether they looked up for 5 seconds or longer or made some comment to the group. The data in the accompanying table were obtained. Use chi square techniques to determine whether group size had an effect on joining. (See Milgram, 1969.) Use the calculation method you did not choose for given problem. Write a conclusion.

Problem
In the late 1930s and early 1940s an important sociology experiment took place in the Boston area. At that time 650 boys (median age = 10½ years) participated in the Cambridge-Somerville Youth Study (named for the two economically depressed communities where the boys lived). The participants were randomly assigned to either a delinquency-prevention program or a control group. Boys in the delinquency-prevention program had a counselor and experienced several years of opportunities for enrichment. At the end of the study, police records were examined for evidence of delinquency among all 650 boys. Analyze the data in the table and write a conclusion.