Yeah thanks guys. I can utilize this update function to help clean things up. It's not as simple as I was hoping though. Also, Bert, by updating the data argument, don't I still have to update the model anyway to take advantage of the extra covariates?
Justin On Wed, Oct 5, 2011 at 12:55 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > Ista: > > But I think the problem here is how to update the model formula. I see no > "simple" way to do that (it can be done straightforwardly enough, but I > wouldn't consider it simple). > > ... But perhaps what you meant is to update the data argument like this: > > cntrl <- data.frame(...) ##response + unchanging base variables > > mdl1 <- lm(resp ~ ., data =cntrl) ## just base covariates > > mdlx <- update(mdl1, data = cbind(cntrl, xdat) ) ## where xdat is data > frame with extra covariates. > > ?formula > > > Cheers, > Bert > > > On Wed, Oct 5, 2011 at 12:37 PM, Ista Zahn <iz...@psych.rochester.edu>wrote: > >> Hi Justin, >> >> On Wed, Oct 5, 2011 at 3:32 PM, justin jarvis >> <littledude.jar...@gmail.com> wrote: >> > Hi all, >> > I am running regressions with many covariates, most of which remain the >> same >> > each time (control variables). Instead of writing 30 demographic >> variables >> > every regression, is there a way I could call them all at once using a >> > variable called, perhaps "demog"? >> >> I would create a base model with just the covariates, and then use >> update() to add other variables. >> >> Best, >> Ista >> >> > >> > I have tried: >> >> demog <- list(age1, age2, age3) but I get an error when I try to call a >> > list in a regression. >> > >> > I also tried: >> >> demog <- cbind(age1, age2, age3) which allows me to run a regression, >> but >> > this is not practical because when I subset the original data set and >> run a >> > regression, this new matrix demog doesn't get subsetted as well, so the >> > variables are of differing length. >> > >> > I'm thinking there is an easy way to do this. Thanks for any help >> > guys/gals. >> > >> > Justin >> > PhD student, >> > University of California, Irvine >> > >> > [[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. >> > >> >> >> >> -- >> Ista Zahn >> Graduate student >> University of Rochester >> Department of Clinical and Social Psychology >> http://yourpsyche.org >> >> ______________________________________________ >> 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. >> > > > > -- > "Men by nature long to get on to the ultimate truths, and will often be > impatient with elementary studies or fight shy of them. If it were possible > to reach the ultimate truths without the elementary studies usually prefixed > to them, these would not be preparatory studies but superfluous diversions." > > -- Maimonides (1135-1204) > > Bert Gunter > Genentech Nonclinical Biostatistics > > > > [[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.
