[R] step method in glm()

From: Birycki Konrad DomBank Warszawa <K.Birycki_at_DomBank.pl>
Date: Thu 13 Jul 2006 - 22:40:43 EST


Hello,  

I estimaded two logit models via glm(). A null model (called glm00) and "full" model with all accessible covariates and interactions between them (glm1).  

Then I tried to get even better model by step procedure. I tried the following code:  

> step(glm00, scope=formula(glm1), method="both")
 

and another one:  

> step(glm00, scope=formula(glm1), method="forward")
 

In both cases step procedure terminated after several steps with a warning:  

> Error in factor.scope(ffac, list(add = fadd, drop = fdrop)) :

            > upper scope does not include model  

What does the word "model" refer to? To glm00 (the null model)? To my knowledge and understanding, the initial null model should have been included in every step of the search.  

Am I wrong?  

Thanks for all comments :-)  

Konrad Birycki  

        [[alternative HTML version deleted]]



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 14 00:04:43 2006

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Fri 14 Jul 2006 - 02:14:15 EST.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.