A research study was conducted to examine the clinical efficacy of a new antidepressant.

Depressed patients were randomly assigned to one of three groups: a placebo group, a group

that received a low dose of the drug, and a group that received a moderate dose of the drug.

After four weeks of treatment, the patients completed the Beck Depression Inventory. The

higher the score, the more depressed the patient. The data are presented below. Compute the

appropriate test.

Placebo Low Dose Moderate Dose 38 22 14 47 19 26 39 8 11 25 23 18 42 31 5