I am trying an automatic model selection for a multiple linear regression using function lm and update. But, I meet a problem when using update. The problem is the function update can not update when variables as a vector(for example,x is a matrix with 100 regression variables). The code is as below:
> model<-lm(y~x1,singular.ok=T,na.action=na.omit)
> for(i in 1:100){
> model<-update(model,.~.+x[,i],singular.ok=T,na.action=na.omit)}
If the above code is represented as below, I can get the correct result. However, I must use the loops.
model<-lm(y~x1,singular.ok=T,na.action=na.omit) model<-update(model,.~.+x[,1],singular.ok=T,na.action=na.omit) model<-update(model,.~.+x[,2],singular.ok=T,na.action=na.omit)
......
model<-update(model,.~.+x[,100],singular.ok=T,na.action=na.omit)
Can anyone help?
Cheers, Lun ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
