Table 2.

A priori analysis to compute the required sample size in a repeated measures ANOVA.

Input		Output
Effect size f	0.25	Noncentrality parameter λ	10.5
α err prob	0.05	Critical F	3.168246
Power (1 − β err prob)	0.8	Numerator df	2
Number of groups	1	Denominator df	54
Number of measurements	3	Total sample size	28
Corr among rep measures	0.5	Actual power	0.8124546
Nonsphericity correction ε	1