Introduction:

For a one-way analysis of variance, the following functions are used:

pwr.anova.test(k = , n = , f = , sig.level = , power = )

where k is the number of groups and n is the common sample size in each group.

For a one-way ANOVA effect size is measured by f where

pi=ni / N

ni=number of observations in group i

N=total number of observations

μi= mean of group i

μ=grand mean

σ²= error variance within groups

Cohen suggests that f values of 0.1, 0.25, and 0.4 represent small, medium, and large effect sizes respectively.