I would like to calculate a sample size for the 2 sample proportion test when the significance level is assumed (0.05), power is assumed (0.90) and I'd like 2 sample proportion test to detect that there is at least 5% difference in proportions in 2 groups (in favour in 1 specific group).
Any idea on how to calcuate this? Or any reference to read?
I've found package in
pwr and a function
pwr.2p.test that enable to calculate a sample with given sig.level, power and given effect but the effect size shoud be delivered as Cohen's d that I can't connect with my desired effect size = at least 5%.
Learn about this from here http://www.statmethods.net/stats/power.html
Thanks for any advce.