Dear Humberto, I suppose you are interessed in the significance of the treatment factor. You can test that effect by comparing models with and without the term. You can get the multiple comparisons with the multcomp package. Here is an example using the Pastes dataset.
library(lme4) library(multcomp) data(Pastes) Model <- lmer(strength ~ cask + (1|batch), data = Pastes) Model2 <- lmer(strength ~ (1|batch), data = Pastes) anova(Model, Model2) glht(Model, linfct = mcp(cask = "Tukey")) confint(glht(Model, linfct = mcp(cask = "Tukey"))) PS You have a lot of treatments to test with few replicates. Testing less treatment with more replicates would be a better design. I'm affraid that the power of your current design will be rather low. HTH, Thierry ------------------------------------------------------------------------ ---- 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.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-sig-ecology-boun...@r-project.org [mailto:r-sig-ecology-boun...@r-project.org] Namens Humberto Dutra Verzonden: dinsdag 8 december 2009 0:25 Aan: r-sig-ecology@r-project.org Onderwerp: [R-sig-eco] pollination experiment with missing value Dear subscribers I performed a quite simple pollination experiment: 12 plants 12 pollination treatments per plant, plant 1 had treatments a, b, c, d... etc plant 2 had treatments a, b, c, d... The idea was to run a simple anova using plants as blocks to see the effects of treatments on fruit production, but I lost some a few treatments in some plants, thus I have to deal with missing values First I tried the obvious, arc transformed fruits > fruset.aov<-aov(arcfruit~treatment+Error(Plant), na.action=na.omit, fruset) but I get the wrong DF because of the missing values, and I cannot perform the multiple comparisons test. Is there a better way to deal with this unbalanced design? I did a little bit more research and I decided to run a GLM for mixed effects using a binomial distribution >y<-cbind(fruits,nofruits) > model<-glmer(y ~ treatment+ (1|Plant), binomial,data=fruset) but them I cannot get the anova table > anova(model,test="F") Error in anova(model, test = "F") : single argument anova for GLMMs not yet implemented Some people suggested using Anova function on the package car, but I don't see how can I get it to work with a mixed effects model like this. Any suggestions are appreciated. Are there other straight forward ways to analyze such data, given the missing values, and multiple comparisons follow up? Thank you Humberto ========================================================== 'Discipline - Success doesn't just happen. You have to be intentional about it, and that takes discipline.' - John Maxwell [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology Druk dit bericht a.u.b. niet onnodig af. Please do not print this message unnecessarily. 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-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology