nat writes: > I want to specify a two-factor model in lme, which should be easy? > Here's what I have: > > factor 1 - treatment FIXED (two levels) > factor 2 - genotype RANDOM (160 genotypes in total) > > I need a model that tells me whether the treatment, genotype and > interaction terms are significant. I have been reading 'Mixed effects > models in S' but in all examples the random factor is not in the main > model - it is a nesting factor etc to specify the error structure. Here > i need the random factor in the model. > > I have tried this: > > height.aov<-lme(height~trt*genotype,data.reps,random=~1|genotype,na.action=na.exclude) > > but the output is nothing like that from Minitab (my only previous > experience of stats software). The results for the interaction term are > the same but F values for the factors alone are very different between > Minitab and R. > > This is a very simple model but I can't figure out how to specify it. > Help would be much appreciated. > > As background: The data are from a QTL mapping population, which is why > I must test to see if genotype is significant and also why genotype is a > random factor. > > Thanks
It seems your message didn't get any replies (at least none posted to r-help). I recentely adjusted such a model (two effects, one fixed, another random, with interaction effects) using lme. I used the following command: z1 <- lme(reacao ~ posicao,data=memoria,random=~1|subject/posicao) Where my model is reacao = mu + posicao (fixed) + posicao*subject (random) + subject (random) Beware though that minitab uses different estimation methods (in lme itself you may use maximum likelihood other restricted m.l) and the results need not to be the same. -- Fernando Henrique Ferraz P. da Rosa http://www.ime.usp.br/~feferraz ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html