Hello,

I am trying to calculate sample size with the parameters below. I used the code below to calculate the sample size but there is no where for me to specify the interval and event frequency. Can anyone help me figure this out. Thank you in advance.

Parameters to include;
power at 95%
the outcome frequency is 10 – 15 events per year total
effect size, 10, 15, 20
Median follow up interval of 3 years
Recruitment of 5 years


/[CODE]
power twoproportions .05 (.10 .15 .20), test(chi2) power(0.95)