
Hi,

I am trying to estimate the sample size needed for the comparison of two groups on a certain measurement, given some previous data at hand. I find that the data collected does not follow a normal distribution, so I would like to use a non-parametric option for sample size calculation.

I found the pwr package but I don't think it has this option and on the internet found that http://www.epibiostat.ucsf.edu/biostat/sampsize.html says only PASS allows non-parametric sample size calculations (although the webpage is not updated).

Any help would be greatly appreciated

Thanks,

Dave
 		 	   		  
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