Chapter 8, Problem 8P

Childhood participation in sports, cultural groups, and youth groups appears to be related to improved self­esteem for adolescents (McGee, Williams, Howden-Chapman, Martin, & Karachi, 2006). In a representa­tive study, a sample of n – 100 adolescents with a history of group participation is given a standardized self-esteem questionnaire. For the general population of adolescents, scores on this questionnaire form a normal distribution with a mean of μ – 50 and a standard deviation of σ = 15 The sample of group participation adolescents had an average of M = 53.8.

a. Does this sample provide enough evidence to conclude that self-eastern scores for these adolescents are significantly different from those of the general population? Use a two-tailed test with α – .05.

b. Compute Cohen’s d to measure the size of the difference.

c. Write a sentence describing the outcome of the hypothesis test and the measure of effect size as it would appear in a research report.