Controlling Within-Subjects Designs We will need a minimum of ___ subjects to use complete counterbalancing with three treatment conditions.
A)2
B)3
C)6
D)9

Question

Quizplus · Accepted Answer

Complete counterbalancing requires that each subject receive every condition in a different order, so the minimum number of subjects needed is equal to the number of possible orders. With three treatment conditions, there are 3! (3 factorial) possible orders: ABC, ACB, BAC, BCA, CAB, CBA. Therefore, we need at least 6 subjects to use complete counterbalancing. Choices A and B are too small, and choice D is too large (although more subjects could be used).

Controlling Within-Subjects Designs We Will Need a Minimum of ___