Thank you Alain and Max for your swift responses. It might be that I'm misunderstanding your responses, but aren't you testing if there is a difference between the two full models? What I want to know, os whether the effect of a specific predictor (x) differs between model1 and model2. I'm not interested (presently) if the fit of model 2 is better than that of model 1 (for instance).
thanks again, Rense On Jan 22, 2007, at 16:26 , Kuhn, Max wrote: > You can use the anova function a la: > >> anova(model1, model2) > Analysis of Variance Table > > Model 1: y ~ x > Model 2: y ~ x + z > Res.Df RSS Df Sum of Sq F Pr(>F) > 1 13 4.4947 > 2 12 4.4228 1 0.0720 0.1952 0.6665 > > I would suggest getting a copy of MASS and/or reading > > http://www.stats.ox.ac.uk/pub/MASS3/Exegeses.pdf > > > Max > > > > ---------------------------------------------------------------------- > LEGAL NOTICE > Unless expressly stated otherwise, this message is confidential and > may be privileged. It is intended for the addressee(s) only. > Access to this E-mail by anyone else is unauthorized. If you are > not an addressee, any disclosure or copying of the contents of this > E-mail or any action taken (or not taken) in reliance on it is > unauthorized and may be unlawful. If you are not an addressee, > please inform the sender immediately. > ______________________________________________ R-help@stat.math.ethz.ch 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.