#1
I am having difficulty understanding how to interpret effect size f(V) on GPower for a priori sample size calculation for ANOVA repeated-measures, within-between interaction. I am conducting an a priori power analysis to calculate sample size for ANOVA repeated measures, within-between interaction. For effect size specifications I have used "as in Gpower 3.0" with the following values:

effect size f = 0.15
α err prob = 0.05
Power (1- β err prob) = 0.8
No. of groups = 2
No. of measurements = 3
Corr among rep measures = 0.5
Nonsphericity correction e = 1
Sample size output = 74.

However, when I click "options" and change the effect size specifications from "As in GPower 3.0" to "As in Cohen 1988 - recommended" the input parameter for effect size becomes f(V) and automatically changes from 0.15 to 0.367 producing the same sample size. Could someone please help me to understand the difference between f(V) and f?