I want to carry out a power analysis on a one group repeated measures experiment using G*power.
I have a group of subjects who tested a set of products. Each subject test one time the products. Hence, I have one observation per cell.
To test the product effect, I used a two anova model with subjects as random effect with proc glm in sas.
I would like to calculate the sample size for a given study having the same design. Given an estimation of effect size, alpha, Beta and an estimation of "a correlation among the repeated measures" could I use the ratio variance of subjets/ (variance of subjects + variance of error) derived from the two way anova model as an estimation of this correlation?