Chapter 4.2, Problem 62E

To determine

To explain how might this knowledge compromise the blinding and why this is an important consideration in the experiment.

Explanation of Solution

In this experiment, the researchers are comparing their new acne treatment against that of the competitor. So, they studied fifty subjects for this study. But the subjects are given the knowledge about that the new acne treatment causes slight redness of the skin. This affect the survey results as the subjects are known about the redness so when their skin becomes red they will be known that they have applied the new acne treatment then they will start judging the new treatment and this in case will eliminate the effect of the same.

In an experiment, if subjects in the control group know that they are receiving a placebo, the placebo effect will be reduced or eliminated; and the placebo will not serve its intended control purpose. Blinding is the practice of not telling subjects whether they are receiving a placebo. Thus, the blinding effect is important for the experiment.