Also look at ?relevel On Wed, Oct 23, 2013 at 7:45 AM, Rafael Moral <rafa_moral2...@yahoo.com.br> wrote: > Thank you very much! > > Best, > Rafael. > > -------------------------------------------- > Em qua, 23/10/13, Bert Gunter <gunter.ber...@gene.com> escreveu: > > Assunto: Re: [R] changing model matrix restriction in lm() > > Cc: "r-help@r-project.org" <r-help@r-project.org> > Data: Quarta-feira, 23 de Outubro de 2013, 11:29 > > ?contrasts > ?C > > Cheers, > Bert > > On Wed, Oct 23, 2013 at 6:00 AM, Rafael Moral > > wrote: > > Dear useRs, > > I was wondering if there was a way of changing the > model matrix restriction automatically in the formula > statement when fitting a model using, for example, lm(). > > When we do > > > > set.seed(100) > > y <- rnorm(12) > > A <- gl(3, 4) > > summary(lm(y ~ A)) > > > > we obtain A1=0 as a baseline and A2 and A3 as effects. > > However, if I want to use A2=0 as a baseline, I can do > > > > X <- cbind(1, model.matrix(lm(y ~ A - 1)))[,-3] > > summary(lm(y ~ X)) > > > > I wonder if there is a way of specifying the > restriction in the parameters directly in the formula > argument instead of building the desired model matrix. > > > > Best wishes, > > Rafael. > > > > ______________________________________________ > > 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. > > > > -- > > Bert Gunter > Genentech Nonclinical Biostatistics > > (650) 467-7374 > > ______________________________________________ > 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.
-- Gregory (Greg) L. Snow Ph.D. 538...@gmail.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.
