As my data was extremely skewed, I have ran 2 non-parametric tests: a Mann-Whitney U and a Wilcoxon Signed Rank test.
I have read that using Cohen's D as an effect size for such tests is not suitable? Assuming that this is correct I have calculated effect sizes using the Z statistic (Z/sqrt of N).
However, once I now have this I am trying to calculate the power? I have tried to use G Power analysis but I think that it assumes the effect size I am entering Cohen's D?
If it is not possible through G.Power. I have been looking for any code on R that would allow me to do this?
Any help would be great! Thanks :)