[EMAIL PROTECTED] (A.J. Rossini) writes: > =?iso-8859-7?q?vasilis=20pappas?= <[EMAIL PROTECTED]> writes: > > > Does anyone know how can I calculate power in wilcoxon.test, > > kruskal. test and oneway.test in an F? I have already found > > power.t.test for calculating power in t.test but it seems that there > > is nothing for the others. Any answer could be useful. Thanks for > > your interest. > > If you can explain exactly how you think power should be computed for > a Wilcoxon, AND it is right (as opposed to a wild ball-park off the > cuff estimate or sensitivity analysis), it'd be a nice journal > article.
Yes. Of course the ARE (asymp.rel.efficiency) of Wilcoxon is .95 in the Normal case, so everyones first guesstimate is to do the power analysis for t and multiply the power by .95 - or divide desired power by .95 and compute N. However, this is highly dependent on distributional assumptions, and the fact that A is for asymptotic is really important even for Normal distributions: for small samples the RE is nowhere near the ARE, so you'd be wise to back things up with some simulations. We do have power.anova.test, though. -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
