Question

athletes who had suffered broken legs were randomly assigned to one of two exercise programs. the first group returned to sports activities in a mean of 60.7 days (with a standard deviation of 28 days). the other group returned to sports in a mean of 51 days (with a standard deviation of 10.7 days).
a) explain why it was important to assign the athletes to the two different treatments randomly.
a. allowing the athletes to choose their own treatments could confound the results.
b. the treatments were assigned randomly so that the negative effects of working out with friends could be neglected.
c. the treatments were assigned randomly so that the positive effects of working out with friends could be neglected.

Explanation:

In experimental design, random assignment helps eliminate confounding variables. If athletes chose their own treatments, factors like their motivation, pre - existing preferences, or other self - selected biases could confound the results (make it hard to tell if the treatment or other factors caused the outcome). Option B and C are incorrect as the random assignment here is not related to working out with friends. So option A is correct.

Answer:

A. Allowing the athletes to choose their own treatments could confound the results.