In an experiment aimed at evaluating the effect of a memory-enhancing drug on the recall of a previously learned response. Either the drug or a placebo was administered to different groups of rats before the memory test. There were three trials of the memory test, and the dependent variable was the time it took the animal to make the correct response.
Why do we not need to use a multiple comparison procedure to compare the drug and control conditions?
A) The difference is obvious.
B) The difference is unimportant.
C) There are only two groups.
D) The test would not be appropriate unless we had at least four groups.

Question

Quizplus · Accepted Answer

There are only two groups (the drug and placebo), so there is no need for a multiple comparison procedure. This procedure is used when there are more than two groups being compared in order to prevent the inflation of type I error (false positives).

In an Experiment Aimed at Evaluating the Effect of a Memory-Enhancing