Help in sample size calculation!

#1
Hello,

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%
 

katxt

Active Member
#2
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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