Chapter 12, Problem AP4.20CPT

To determine

To find out why a random assignment is a part of a well-designed comparative experiment.

Answer to Problem AP4.20CPT

Option (b) is the correct option.

Explanation of Solution

We use random assignment in a well-designed comparative experiment because we want the different treatment groups to be as similar as possible such that there are no differences among the treatment groups before the treatment and thus we can then be sure that the differences are due to the treatments themselves.

Thus, option (b) is the correct option as it helps create roughly equivalent groups before treatments are imposed on the subjects.