Help in sample size calculation!


I’ve made a retrospective research and did a sample size calculation and I cannot find the formula I used and cannot get to this number! I need to present my study next month!

n=720, power=80%, p0=0.15, margin of error=5%


Well-Known Member
Your figures don't seem to be in the normal form.
Perhaps you mean effect size = 0.15 and significance level = 0.05
Or are you talking about proportions?
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