[R] When to use quasipoisson instead of poisson family

ronggui ronggui.huang at gmail.com
Tue Apr 10 07:25:55 CEST 2007

It seems that MASS suggest to judge on the basis of
sum(residuals(mode,type="pearson"))/df.residual(mode). My question: Is
there any rule of thumb of the cutpoiont value?

The paper "On the Use of Corrections for Overdispersion"  suggests
overdispersion exists if the deviance is at least twice the number of
degrees of freedom.

Are there any further hints? Thanks.

Ronggui Huang
Department of Sociology
Fudan University, Shanghai, China

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