I haven't done much with the type of data you're working with, but  
here is a post that lists a few packages for doing sample size  
calculations in R.  Perhaps one of them will be helpful.

https://stat.ethz.ch/pipermail/r-help/2008-February/154223.html

Andrew Miles

On Sep 27, 2010, at 2:09 PM, Paul Miller wrote:

> Hello Everyone,
>
> I'm trying to conduct a couple of power analyses and was hoping  
> someone might be able to help. I want to estimate the sample size  
> that would be necessary to adequately power a couple of non- 
> inferiority tests. The first would be a log-rank test and the second  
> would be a Wilcoxon rank-sum test. I want to be able to determine  
> the sample size that would be necessary to test for a 3 day  
> difference in median recovery time between 2 groups of cancer  
> patients.
>
> Both of these tests are infeasible using SAS Proc Power and I  
> haven't been able to find information about how to do them using  
> either SAS or R.
>
> Does anyone know how to perform either of these calculations? If so,  
> I'd greatly appreciate it if you could share a couple of examples.
>
>
> Thanks,
>
> Paul
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


	[[alternative HTML version deleted]]

