Dear R users, I have used the following model:
M1 <- gls(Nblad ~ Concentration+Season + Concentration:Season, data=DDD, weights=varIdent(form=~ 1 | Season*Concentration)) to assess the effect of Concentration and Season on nitrogen uptake by leaves (Nblad). I accounted for the difference in variance across the factor levels by using the varIdent function. Then I wanted to perform multiple comparisons with the glht function of the multcomp package. glht(M1,linfct = mcp(Season = "Tukey")) However, here I got an error message "Error in terms.default(object) : no terms component. Error in factor_contrasts(model) : no ‘model.matrix’ method for ‘model’ found!". Does the glht function work with a gls model? And if not, is there an other way to perform multiple comparisons for a gls model? I've searched this forum for an answer to this question, but I could only found someone with the same question which remained unanswered. I hope someone can provide an answer now! Many thanks in advance! Sandy -- View this message in context: http://r.789695.n4.nabble.com/multiple-comparisons-with-generalised-least-squares-tp3441513p3441513.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
