Dear Christoph, Why should (1) not work? As long as you have enough levels, it should not be a problem. You need at least 6 levels for each random effect. When you have less than six levels, then you better move those variables to the fixed effects.
An example: 2 blocks with each 2 plots. Each plot has 2 subplots. A subplot contains 8 individuals. In this case you have 2 blocks, 4 plots, 8 subplots and 64 individuals. So the model will look like: y~explanatory.variables + block/plot, random=~time|subplot/individual Another example: 6 blocks with each 2 plots. Each plot has 2 subplots. A subplot contains 3 individuals. In this case you have 6 blocks, 12 plots, 24 subplots and 72 individuals. So the model will look like: y~explanatory.variables, random=~time|block/plot/subplot/individual 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 thierry.onkel...@inbo.be 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: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Namens Christoph Scherber Verzonden: donderdag 20 augustus 2009 11:33 Aan: r-h...@stat.math.ethz.ch Onderwerp: [R] nested, repeated measure lme Dear all, Suppose I have a nested, repeated measure lme model. Which of the following formulae is correct? (assuming data are sampled from several plots in an agricultural experiment) (1) y~explanatory.variables,random=~time|block/plot/subplot/individual (2) y~explanatory.variables,random=~time|unique.ID.of.every.individual I have read that (2) is the only approach that works. But how could I then still include the nesting information from (1)? Many thanks for your help! Best wishes Christoph (using R 2.9.0 and the nlme library on Windows XP) -- Dr. rer.nat. Christoph Scherber University of Goettingen DNPW, Agroecology Waldweg 26 D-37073 Goettingen Germany phone +49 (0)551 39 8807 fax +49 (0)551 39 8806 Homepage http://www.gwdg.de/~cscherb1 ______________________________________________ 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. Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document. ______________________________________________ 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.
