Hi,

This is a late announcement for a package that has been up on CRAN since Feb 2006. 

The package is called ssanv and it calculates sample sizes for two group tests with adjustments for nonadherence and variability of the input parameters. As an example, suppose you want a sample size for a two group difference in normal means but you get your estimate of your variance from a previous study. Then with this package, you can account for the variability of that variance estimate in your sample size calculations. The details are described in:



		Fay, MP, Halloran, ME, Follmann, DA. Accounting for Variability in Sample Size Estimation with Applications to Nonadherence and Estimation of Variance and Effect Size. Biometrics 2007, 63: 465-474. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1541-0420.2006.00703.x


Please let me know of any problems with the package or have any comments.

Thanks, 


Mike



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Michael P. Fay, PhD
Mathematical Statistician
National Institute of Allergy and Infectious Diseases
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