A therapist would like to evaluate the effectiveness of a procedure for treatment depression. A sample of n=16 depress
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 clients level of depression is measured again. For this example, the average level of depression dropped by Md=6.8 points following therapy. The difference score had a variance of s^2=64.
a) Do these data indicate a significant change in depression depression? Use a two tailed test at the .05 level of significance.
b) Compute Cohen's d to measure the size of the treatment effect.