Simply do this: lm(y ~ I(X1 - X2))
Ravi. ____________________________________________________________________ Ravi Varadhan, Ph.D. Assistant Professor, Division of Geriatric Medicine and Gerontology School of Medicine Johns Hopkins University Ph. (410) 502-2619 email: rvarad...@jhmi.edu ----- Original Message ----- From: "CE.KA" <ce.kay...@yahoo.fr> Date: Friday, October 30, 2009 7:48 pm Subject: Re: [R] Multiple linear regression with constraint (imposition) To: r-help@r-project.org > Sorry there was a mistake: > > Hi R users > > I want to do a multiple linear regression with R > > With a normal model (Y=Cste+A1*X1+A2*X2) the program would be > lm(Y~X1+X2) > > My model is Y=Cste+A1*X1+A2*X2 with the constraint A1=-A2 > What is the program for such a model? > > Best regards > > > -- > View this message in context: > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > > PLEASE do read the posting guide > 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.