Dear Thierry, Thanks for the reply. But as you may read in the paper http://bioinformatics.oxfordjournals.org/cgi/content/abstract/22/18/2244 when the sample sizes are not the same there may be an increase in the Type I error rate. Comments will be appreciated. Best regards, João Fadista
________________________________ De: ONKELINX, Thierry [mailto:[EMAIL PROTECTED] Enviada: ter 08-04-2008 15:27 Para: João Fadista; r-help@r-project.org Assunto: RE: [R] permutation test assumption? Dear João, You can do permutation tests on an unbalanced design. HTH, Thierry ---------------------------------------------------------------------------- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 [EMAIL PROTECTED] www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey -----Oorspronkelijk bericht----- Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens João Fadista Verzonden: dinsdag 8 april 2008 15:18 Aan: r-help@r-project.org Onderwerp: [R] permutation test assumption? Dear all, Can I do a permutation test if the number of individuals in one group is much bigger than in the other group? I searched the literature but I didin´t find any assumption that refers to this subject for permutation tests. Best regards João Fadista Ph.d. student UNIVERSITY OF AARHUS Faculty of Agricultural Sciences Dept. of Genetics and Biotechnology Blichers Allé 20, P.O. BOX 50 DK-8830 Tjele Phone: +45 8999 1900 Direct: +45 8999 1900 E-mail: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> Web: www.agrsci.org <http://www.agrsci.org/> ________________________________ DJF now offers new degree programmes <http://www.agrsci.org/content/view/full/34133> . News and news media <http://www.agrsci.org/navigation/nyheder_og_presse> . This email may contain information that is confidential. Any use or publication of this email without written permission from Faculty of Agricultural Sciences is not allowed. If you are not the intended recipient, please notify Faculty of Agricultural Sciences immediately and delete this email. [[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.