Thank you. Most of the answers solved the puzzles. Q2
> > I tried to display sub-model with only temp_ran using the code below but > > failed. > > Please kindly suggest the potential failure cause. > > > > code > > > > library(MuMIn) > > datam <-read.csv("c:/migration/Mig_ratio_20100817.csv",header=T, > > row.names=1) > > > mig.stds <-lm(SummerM_ratio ~ temp_max + evi_mean + topo_var + > topo_mean + coast + Iso_index_0808, > ## now tell R were to find the variables in formula > data = datum.std) > ## If you are fitting a Gaussian GLM it is better fitted with lm() > => Please explain why fitted lm is better for GLM. > > > > But temp_ran is not in your model... > > > error in eval(expr, envir, enclos), 'temp_ran' not found > > When used properly (none of this datam.std$ business), subset will do > what you want: > > > dd2 <- dredge(lm1, subset = X1) > > dd2 > Global model: lm(formula = y ~ ., data = Cement) > --- > Model selection table > (Int) X X1 X2 X3 X4 k R.sq Adj.R.sq RSS > 3 52.58 1.4680 0.6623 4 0.9787 0.9744 57.90 > > => Please suggest how to define subset in my case Finally, it would be highly appreciated to recommend any references of R for a beginner like me. Elaine [[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.