Hello, I have a doubt in using the function step (step wise) to select glm models.
Usually I apply the gamma distribution to analyze fishery data. To select the terms I use a routine where I first compare single term models to the null model (eg. U~1 vs. U~depth; U~1 vs. U~latitude; etc. where U= abundance) and, by means of the result given by a likelihook function applied for each comparison, I select the strongest effect, lets say depth. Then I run a new step comparing the U~depth vs. U~depth+latitude; U~depth vs. U~depth+... etc. Making this way I put the terms in magnitude order. I tried to make a gaussian model using the step(glm.model) function to select the terms but I saw that in the output table given by anova(glm.model) the selected terms kept the original order. Is it possible to have the terms in the model rearranged, as in my example? Thanks for any help. I read Chambers and Hasties Statistical Models in S, Venables and Ripley Modern Applied Statistics and, of course, R help but I couldnt get the trick. Antonio -- Biologist Sao Paulo Fisheries Institute ------------------------------------------------- WebMail Bignet - O seu provedor do litoral www.bignet.com.br ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
