Petr PIKAL wrote: > Hi > > [EMAIL PROTECTED] napsal dne 14.09.2007 13:50:58: > > >> 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 >>> >>>>>>>> >>>>>>>> > > > <snip> > > > >>>> 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 >> > > But as Birgit actually does not have any paired values, according to the > data she had sent, she can not do paired t.test at all. The only way is to > compare averages from each vector by non paired t.test or to get some new > values for which she have counterparts. > True, for that particular set of data. I did make that point in my first reply (tried to, anyways), but I didn't repeat it the second time.
If you look back, you'll see that Birgit was also doing TTest75<-t.test(Fem75, Mal75, alternative= "two.sided", paired= TRUE) and presumably there are several similar sets of data. This "works" in the sense that it produces a test, but one could get the suspicion that it is only using a small subset of available data if the dropout rate is approaching that of Fem66/Mal66. Hence the discussion of the general case. > Regards > Petr > > > > >>> 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. >> > > ______________________________________________ > 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. > -- 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.
