racmar wrote > > I have also been searching various forums and books to see if there are > any methods I could use and have only found people, such as yourself, > asking the same question. >
I was looking into this recently, as well, and found that the problem has to do with building the model.matrix/terms/model.frame for gls objects when using the glht function. I ended up creating three gls-specific functions and was able to get estimates/confidence intervals for the toy example below. You may find these functions useful (under the caveat that I only checked that I got estimates and not that the estimates were correct ;) ). Ariel Example: library(nlme) Orthodont$fage <- factor(Orthodont$age) #toy example with Orthodont data using age as a factor fitgls <- gls( distance ~ fage, data=Orthodont, weights = varIdent(form =~1|fage)) library(multcomp) #notice the error about the model.matrix for gls objects when using glht confint( glht (fitgls, mcp(fage="Tukey") )) #create model.frame, terms, and model.matrix functions specifically for gls objects model.matrix.gls <- function(object, ...) model.matrix(terms(object), data = getData(object), ...) model.frame.gls <- function(object, ...) model.frame(formula(object), data = getData(object), ...) terms.gls <- function(object, ...) terms(model.frame(object),...) #now run glht again confint( glht( fitgls, mcp(fage="Tukey") )) -- View this message in context: http://r.789695.n4.nabble.com/multiple-comparisons-with-generalised-least-squares-tp3441513p4636009.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.