In a within-subjects 2x3x4 factorial ANOVA, how many groups (cells) are formed?

In a within-subjects 2x3x4 factorial ANOVA, how many groups (cells) are formed?

• A. 1, because it is WITHIN subjects
• B. 8 groups
• C. 12 groups
• D. 24 groups

Answer: (A)

In a factorial ANOVA, the number of cells equals the product of the levels of each factor. Here you have 2 levels for the first factor, 3 for the second, and 4 for the third. Multiply them: 2 × 3 × 4 = 24. In a within-subjects design, the same participants are measured in every cell, so there isn’t 24 separate groups of different participants; there is one group of participants contributing data to all 24 conditions. The repeated measures affect error structure and power, not the number of cells. So there are 24 cells.

In a factorial ANOVA, the number of cells equals the product of the levels of each factor. Here you have 2 levels for the first factor, 3 for the second, and 4 for the third. Multiply them: 2 × 3 × 4 = 24. In a within-subjects design, the same participants are measured in every cell, so there isn’t 24 separate groups of different participants; there is one group of participants contributing data to all 24 conditions. The repeated measures affect error structure and power, not the number of cells. So there are 24 cells.