A psychologist would like to determine whether there is a relationship between depression and aging. It is known that the general population averages μ = 40 on a standardized depression test. The psychologist obtains a sample of n = 9 individuals who are all more than 70 years old. The depression scores for this sample are as follows: 37, 50, 43, 41, 39, 45, 49, 44, 48.
a. On the basis of this sample, is depression for elderly people significantly different from depression in the general population? Use a two-tailed test with α = .05.
b. Compute the estimated Cohen's d to measure the size of the difference.
c. Write a sentence showing how the outcome of the hypothesis test and the measure of effect size would appear in a research report.