A researcher is interested in how well a new anti-depressant drug works for people with mild depression. She recruits a group of 120 people with mild depression, measures their depression, and randomly allocates them into three conditions. The first condition receives a treatment of the drug for two weeks. The second condition believes that they are taking the drug for two weeks, but in fact they are given sugar pills. The third condition is a control group who are given nothing to take. After two weeks, the first two groups each show large improvements of a similar magnitude, while the third group show no improvement. The results of this study suggest a strong:
A) effect of the anti-depressant drug.
B) placebo effect.
C) effect of evaluation apprehension.
D) carryover effect.

Question

Quizplus · Accepted Answer

The fact that the second condition (placebo group) also showed a large improvement suggests that the improvement in the first condition (drug group) may be due to the placebo effect rather than the drug itself. The control group did not show any improvement, ruling out other potential factors such as evaluation apprehension or carryover effects. Therefore, the strongest conclusion from this study is that there was a strong placebo effect.

A Researcher Is Interested in How Well a New Anti-Depressant