In an experiment testing the prediction that a certain drug prevents cataracts in females over the age of 65, which control should be used?
A) male subjects
B) female subjects younger than 65
C) alternative drugs that are suspected to prevent cataracts
D) female subjects over 65 that are given placebos

Question

Quizplus · Accepted Answer

The best control in this experiment would be female subjects over 65 that are given placebos. This allows for comparison of the effects of the drug on cataracts in the treatment group versus the non-effect of the placebo in the control group. Using males or younger females as controls would not provide a fair comparison, as the drug may have different effects in different populations. Using alternative drugs as controls would not allow for isolation of the effects of the specific drug being tested.

In an Experiment Testing the Prediction That a Certain Drug