On Tue, 2010-10-12 at 19:37 +0800, elaine kuo wrote: > Dear List, > > I want to ask a AIC question based on package library(MuMIn) > > The relative importance of 16 explanatory variables > > are assessed using delta AIC in a generalized linear model. > > > Please kindly advise if it is possible to show models
Using the below example you quote: dd <- dredge(lm1, subset = X1 & X2) > > with any two only certain variables. If you are now going to ask how can I select only those models with two variables in, this: dd <- dredge(lm1) parms <- !is.na(dd[, -c(1, (ncol(dd) - c(0:7)))]) want <- which(rowSums(parms) == 2) dd[want, ] will do it, again using the example you quote. HTH G > Thank you. > > > Elaine > > I asked a similar question and got a great help for models > > with only one variable as below. > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > In effect, you want > > data(Cement) > lm1 <- lm(y ~ ., data = Cement) > dd <- dredge(lm1, subset = X1) > > want <- with(dd, is.na(X) & is.na(X2) & is.na(X3) & is.na(X4)) > want > ## how many models selected? > sum(want) > ## OK selected just 1, show it > dd[want, , drop = FALSE] > > Oh, actually, I suppose you could automate this, so it will return all > models with single variable: > > dd <- dredge(lm1) > parms <- !is.na(dd[, -c(1, (ncol(dd) - c(0:7)))]) > want <- which(rowSums(parms) == 1) > dd[want, ] > > Having said all this, I don't think this is a good way to do model > selection. > > G > > [[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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ 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.
