A doctor who believes strongly that antidepressants work better than "talk therapy" tests depressed patients by treating half of them with antidepressants and the other half with talk therapy. After six months the patients are evaluated on a scale of 1 to 5, with 5 indicating the greatest improvement. Answer parts (a) through (d) below. a. The doctor is concerned that if his most severely depressed patients do not receive the antidepressants, they will get much worse. He therefore decides that the most severe patients will be assigned to receive the antidepressants. Explain why this will affect his ability to determine which approach works best. A. If the doctor decides on the treatment, this could introduce bias. B. The doctor is assigning all antidepressants to only the most severely depressed people. OC. The doctor is letting his empathy get in the way of treating the patients objectively. This may cause personal issues for either the doctor or the patients over the course of the treatment. OD. The doctor is creating a second treatment group that is dependent on the severity of the patient's depression. This will further confound the results. b. What advice would you give the doctor to improve his study? OA. The doctor should remain as objective as possible in order to increase the chances of successfully treating the patients. OB. The doctor should remove the least depressed people from the study. OC. The doctor should divide the patients into groups based on how depressed they are, and give out a certain percentage of antidepressants to the least depressed group, a higher percentage to the more depressed group, and so on. OD. The doctor should randomly assign the patients to the different treatments. OE. The doctor must give an equal number of antidepressants to the least depressed patients and the most depressed patients in order to make the treatment sufficiently random.