Dear list, I'm trying to fit a glm model using family=poisson(link = "identity"). The problem is that the glm function fits a model with a negative intercept, which sounds like a nonsense to me, being the response a Poisson variable. >From a previous discussion on this list I've understood that the glm function uses IRLS for the fitting without any constraint so it is possible for it to end up in a region of values which are not admissible given the model, and in fact sometimes it fails asking for valid starting values. In this case I expected it to fail asking to supply starting values, and instead it fits the model just nice with this negative intercept. What am I missing?
Thanks, Cheers Federico ______________________________________________ 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