A therapist would like to evaluate the effectiveness of a
procedure for treating depression. A sample of n = 9 depressed
clients is obtained and each person's level of depression is
measured using a standardized questionnaire before they begin the
therapy program. Two weeks after therapy, each client's level of
depression is measured again. For this sample, the average level of
depression dropped by MD = 4.7 points following therapy. The
difference scores had a variance of s2 = 36. Do these data indicate
a significant change in depression? Use a two-tailed test with
alpha level = .01. (8 points)