When participant responding is not consistent,the one-way within-subjects ANOVA can actually have less power to detect an effect than the one-way between-subjects ANOVA.

Question

Quizplus · Accepted Answer

This is true. When there is inconsistency in participant responding, the within-subjects ANOVA may have greater error variance, which will decrease the power of the test to detect true differences between conditions. In contrast, the between-subjects ANOVA assumes that each subject represents a unique level of the independent variable, and therefore individual variability is not confounded with the effects of the independent variable. This can result in a more powerful test, particularly if the individual differences are large enough that they obscure the effects of the independent variable in the within-subjects design.

When Participant Responding Is Not Consistent,the One-Way Within-Subjects ANOVA Can