[R] When to use quasipoisson instead of poisson family

[ronggui]

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