A Cosmetics Company Wants to Market a New Suntan Lotion

Multiple Choice

A cosmetics company wants to market a new suntan lotion. The developers recruit 10 volunteers for their study to test the effectiveness of the new lotion. Each volunteer was given the old lotion on one arm, randomly selected, and the other lotion on the other arm. The volunteer was then asked to expose both arms to the sun. The time was measured until there was visible redness in one arm, which was then shielded from the sun. The experiment ended when the other arm showed signs of redness. Below are the times for both arms for each subject. This study design is called:

A) a left vs. right design.
B) a same subject design.
C) a matched pairs design.
D) a before and after design.