[R] Power of t-test in R vs. S-PLUS

Alan T. Arnholt arnholt at cs.appstate.edu
Fri Mar 1 22:14:36 CET 2002

Could someone shed some light on the statement from Thomas 
that "(with sampling uncertainties of about +/- 2% in each 
number)".  What exactly is being said about the accuracy of 
the simulation and how is that number +/-2% being 



> So at 0.548882 there is about 80% power, at 0.4322771 there is about 55%
> power (with sampling uncertainties of about +/- 2% in each number).
> It is interesting to note that a simulation shows the unequal-variance
> t-test to have only 75% power at 0.5488882, indicating the sensitivity of
> the power calculations at this sample size.
> 	-thomas
> Thomas Lumley			Asst. Professor, Biostatistics
> tlumley at u.washington.edu	University of Washington, Seattle

Alan T. Arnholt
Associate Professor
Department of Mathematical Sciences
Appalachian State University

Tel: (828) 262-2863
Fax: (828) 265-8617


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