Mark Na <mtb954 <at> gmail.com> writes: > > Dear R-helpers, > I would like to compare the fit of two models, one of which I fit using lm() > and the other using glm(family=poisson). The latter doesn't provide > r-squared, so I wonder how to go about comparing these > models (they have the same formula). > > Thanks very much, > > Mark Na > I'm not sure what you are trying to do but it might be informative to compare the diagnostic plots from the fits. Remember that Poisson distributed data is heteroscedastic, mean = variance, which isn't the default hypothesis when fitting with lm. Also, the default link function with the poisson family is log. So, these are things to take into account in any potential comparison.
Ken -- Ken Knoblauch Inserm U846 Stem-cell and Brain Research Institute Department of Integrative Neurosciences 18 avenue du Doyen Lépine 69500 Bron France tel: +33 (0)4 72 91 34 77 fax: +33 (0)4 72 91 34 61 portable: +33 (0)6 84 10 64 10 http://www.sbri.fr/members/kenneth-knoblauch.html ______________________________________________ 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.
