A clinical psychologist is interested in evaluating the effectiveness of the following three techniques for treating mild depression:cognitive restructuring, assertiveness training, and an exerciseutrition program. Forty undergraduate students suffering from mild depression are randomly sampled from the university counseling center's waiting list and randomly assigned 10 each to the three techniques previously mentioned and the remaining 10 to a placebo control group.Treatment is conducted for 10 weeks, after which depression is measured using the Beck Depression Inventory. The post-treatment depression scores are given here.Higher scores indicate greater depression.

Treatment Placebo Cognitive Assertiveness Exerciseutrition restructuring training 27 10 16 26 16 8 18 24 18 14 12 17 26 16 15 23 18 18 9 25 28 8 13 22 25 12 17 16 20 14 20 15 24 9 21 18 26 7 19 23