Birgit Lemcke wrote: > > Am 14.09.2007 um 12:05 schrieb Peter Dalgaard: > >> S Ellison wrote: >>> >>>>>> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>> >>>>>> >>>>> So what can I do now to solve my problem? >>>>> >>>>> Do you think I should not use paired=TRUE? >>>>> >>>> You *can* only use it when you have pairs, and you must do it then, to >>>> correct for intra-pair correlation. The drawback is that it looks only >>>> at complete pairs, throwing away all the singlets. It is possible to >>>> recover the information from the singlets , basically by combining a >>>> paired test for the pairs and an unpaired one for the singlets. >>>> (Someone >>>> must have written this down, but I'm afraid I don't have a nice >>>> reference). >>>> >>> >>> Question: Could you achieve this kind of outcome with lme? stack the >>> two groups, mark the observations y by subject (ie the pair ID) and >>> group (treatment, presumably), and do something like >>> >>> anova(lme(y~group, data=d, random=~1|subj, na.action=na.omit)) >>> >>> Or is that just disguising one of those nasty unbalanced 2-way anova >>> problems? >>> >> Yes, but.... >> >> I don't think lme() will do better than what you can do by hand: Get two >> independent estimates of mu1-mu2 (one estimate from the pairs and one >> from the singlets), compute a weighted average using the s.e.'s and test >> that against zero (possibly after testing them for equality for good >> measure). This is easy if you use a plug-in approach: first assume that >> the s.e. are known, then plug in their empirical value. The tricky bit >> is to calculate the DF in the style of Welch's test. > > I apologise but I really can not follow your explanations. > I am R and Stastistics Beginner. > > What do you mean with mu1-mu2 and what are s.e.´s? > That was a reply to S. Ellison. If you don't understand it, don't worry; you'll probably need to read a book chapter or more about weighted analyses to get up to speed for that.
mu1, mu2 : (theoretical) mean for group 1, 2 s.e.: standard error > Once again thank you for your help. > > Birgit > > > > >> >> -- O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B >> c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K >> (*) \(*) -- University of Copenhagen Denmark Ph: (+45) >> 35327918 >> ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) >> 35327907 >> >> > > Birgit Lemcke > Institut für Systematische Botanik > Zollikerstrasse 107 > CH-8008 Zürich > Switzerland > Ph: +41 (0)44 634 8351 > [EMAIL PROTECTED] > > > > > > -- O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ 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.
