Understanding the output from lme anova
Dear Peter, A * B is just a shorthand notation for A + B + A:B The model will auto-expand those term to the ":" notation. Best regards, Thierry PS Creating the factors in your dataset and the use of spaces will increase the readability of your code! ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek team Biometrie & Kwaliteitszorg Gaverstraat 4 9500 Geraardsbergen Belgium Research Institute for Nature and Forest team Biometrics & Quality Assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 Thierry.Onkelinx at 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-sig-ecology-bounces at r-project.org [mailto:r-sig-ecology-bounces at r-project.org] Namens Hedberg Peter Verzonden: maandag 6 december 2010 15:46 Aan: r-sig-ecology at r-project.org Onderwerp: [R-sig-eco] Understanding the output from lme anova Dear all. I have a question regarding how to interpret the output from my lme.anova. My model looks like this lme_Cyperaceae<-lme(Cyperaceae~Site+Ditch_block+Tree_cut+as.fa ctor(Dist_start)+((as.factor(Dist_start))*Tree_cut)+((as.facto r(Dist_ditch))/Ditch_block),random=~1|Mainplot/Transect/Obsplot) My question concerns that I use the divission sign to indicate nesting in ((as.factor(Dist_ditch))/Ditch_block), and I use * to indicate two-way interaction in ((as.factor(Dist_start))*Tree_cut), but in the output both terms are presented with a colon (:) sign. Tree_cut:as.factor(Dist_start) 3 6 0.259899 0.8520 Ditch_block:as.factor(Dist_ditch) 4 56 2.695738 0.0399 Is there something wrong in how I wrote the model, or is the colon sign used for all interactions weather nested or the * type. Would be greatly thankful for any help in understanding this. The output mentioned above is from an analysis of lme.anova on the result of the lme model. Best regards, Petter Hedberg
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