09-15-2016 10:29 AM
I want to calculate sample size per group to test proportions if i think and response rate is 1% and i want to detect a difference of 0.5% with power 90%.
I run this:
Is that correct for what i want to do? I get ~10,400 per group
I tried doing this for response rate 3% and detect a difference of 0.5% with 90% power. Logically i thought the Nper group would be smaller since the response rate is higher but its more. Which makes me think that i am doing something wrong.