



Dear Help-list, How can I do a multiple comparison test (mct) on selected contrasts from a linear model while using packages lme4 and multcomp?  I am running R 2.13.0 under Windows 7.  The following linear model and mct produces a global mct of 15 paired contrasts of the combined (Site, Position) factor SitePos of which only 9 are of interest.  Model.G = lmer(log10(SrCa) ~ SitePos + (1 | Eel), data = Data1)
Model.G.mct = glht(Model.G, linfct = mcp(SitePos = "Tukey"))summary (Model.G.mct)  The following code creates the desired reduced set of contrasts but I have been unable to apply it correctly to the mct.   contr = rbind("CR core - MH core" = c(1,0,0,-1,0,0),"CR core - CR edge" = c(1,0,-1,0,0,0),
"CR core - CR EC" = c(1,-1,0,0,0,0,0),"CR edge - MH edge" = c(0,0,1,0,0,-1),
"CR edge - CR EC" = c(0,-1,1,0,0,0),"CR EC - MH EC" = c(0,1,0,0,-1,0),
"MH core - MH edge" = c(0,0,0,1,0,-1),"MH core - MH EC" = c(0,0,0,1,-1,0),
"MH edge - MH EC" = c(0,0,0,0,-1,1)) Execution of this code produces the error message: In rbind ('CR core - MH core" = c(1,0,0,-1,0,0), etc.: number of columns of results is not a multiple of vector length (arg 1)'.  
Model.G.mct2 = glht(Model.G, linfct = mcp(SitePos = contr))  #execution produces "Error in linfct{[nm]} %*% c: non-comformable argument", as a consequence of the previous error
summary (Model.G.mct2, test = adjusted(summarytype = "single-step")) Clearly, this approach is incorrect (and I have tried others).  How can I introduce the selected set of contrasts into the mct?  Thanks for any help provided.  Regards,B. Jessop 		 	   		  
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