Dear Jordan, Oddly, essentially the same question was posed by someone else three days ago.
Because groups enters the model additively, the proper test for each contrast is just the t-test for the corresponding coefficient in the summary() for the model. I hope this helps, John ------------------------------------------------ John Fox Sen. William McMaster Prof. of Social Statistics Department of Sociology McMaster University Hamilton, Ontario, Canada http://socserv.mcmaster.ca/jfox On Mon, 9 Jul 2012 20:06:22 +0100 Jordan Ramsey <jmr...@cam.ac.uk> wrote: > I'm wondering if anyone would be able to help me out. I'm trying to use a > type II ANOVA for a model with user-specified contrasts and covariates. > > I have two treatment groups and a control group. I'm comparing average > treatment to controls and also between the two treatment groups, but I'm > also looking to adjust for age and gender as covariates: > > contrastMat=cbind(c(-1,-1,2),c(1,-1,0)) > contrasts(groups)=contrastMat > > Model=lm(Response~Age+Gender+Age:Gender+groups) > > since I'm interested in SS(R | A,G,AG) > > I was hoping then to use the Anova() function in the car() package to find > the type II ANOVA for my specified contrasts, but when I do so it only > looks at Response as a whole instead of the two contrasts. Any ideas where > I'm going wrong? > > Thanks, > JR > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. / ______________________________________________ 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.
