Use the quasibinomial family -- see the help pages. Warning: how are you estimating the over-dispersion? The estimate given by the residual deviance can be badly biased.
I don't know your reference, but this is all in McCullagh & Nelder (1989) and earlier. On Tue, 18 Feb 2003, Hardouin Lo�c wrote: > I am performing glm with binomial family and my data show slight > overdispersion (HF<1.5). Nevertheless, in order to take into account for > this heterogeneity though weak, I use F-test rather than Chi-square > (Krackow & Tkadlec, 2001). But surprisingly, outputs of this two tests > are exactly similar. What is the reason and how can I scale the output > by overdispersion ?? -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
