(This article was first published on

**Quantitative Ecology**, and kindly contributed to R-bloggers)This is a small function Venables and Ripley provide in their MASS book. You don’t need it anymore because vcov() has a method for the glm class. However, it is useful to see how to extract bits from a fitted model object.

vcov.glm<-function(obj){

#return the variance-covariance matrix of a glm object

#from p. 188 in Venables and Ripley. 2002.

#Modern Applied Statistics With S. Springer. New York.

so <- summary(obj,corr=F)

so$dispersion * so$cov.unscaled

}