On 1/22/2008 9:50 AM, Fränzi Korner wrote: > Hello > > > > how can I predict from a lm-object over a range of values of one explanatory > variable without having to specify values for all the other explanatory > variables? > > > > e.g. > > > > mod<-lm(y~x1+x2+x3+x4) > > > > x1.new<-seq(0, 100) > > predict(mod, new=list(x1=x1.new)) > > > > > > Here, predict() does not work, since values for x2, x3 and x4 are missing. > Is there a function or argument that, in such a case, averages or weights > over the other explanatory variables, how it is done in Genstat?
You might consider effect() in the effects package by John Fox. For example: library(effects) mod.pres <- lm(prestige ~ log(income, 10) + poly(education, 3) + poly(women, 2), data=Prestige) effect("poly(women,2)", mod.pres, xlevels=list(women = seq(0,100,20))) poly(women,2) effect women 0 20 40 60 80 100 47.71028 45.12385 44.53749 45.95121 49.36499 54.77883 > Thanks > > Fränzi > > > > > > ************************************************************************ > > Dr. Fränzi Korner-Nievergelt > > oikostat - Statistische Analysen und Beratung > > Ausserdorf 43 > > CH - 6218 Ettiswil > > Tel.: +41 (0) 41 980 49 22 > > www.oikostat.ch > > > > ************************************************************************* > > > > Schweizerische Vogelwarte > > CH - 6204 Sempach > > > > www.vogelwarte.ch > > ************************************************************************* > > > > > [[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. -- Chuck Cleland, Ph.D. NDRI, Inc. 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894 ______________________________________________ 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.