[R] computation of dispersion parameter in quasi-poisson glm

2010-04-09 Thread Sven Garbade
Hi list, can anybody point me to the trick how glm is computing the dispersion parameter in quasi-poisson regression, eg. glm(...,family=quasipoisson)? Thanks regards, Sven __ R-help@r-project.org mailing list

Re: [R] computation of dispersion parameter in quasi-poisson glm

2010-04-09 Thread Achim Zeileis
On Fri, 9 Apr 2010, Sven Garbade wrote: Hi list, can anybody point me to the trick how glm is computing the dispersion parameter in quasi-poisson regression, eg. glm(...,family=quasipoisson)? It's the sum of squared Pearson residuals divided by the residual degrees of freedom. For example:

Re: [R] computation of dispersion parameter in quasi-poisson glm

2010-04-09 Thread Prof Brian Ripley
On Fri, 9 Apr 2010, Sven Garbade wrote: Hi list, can anybody point me to the trick how glm is computing the dispersion parameter in quasi-poisson regression, eg. glm(...,family=quasipoisson)? It isn't. glm() does not need (and does not compute) the dispersion parameter. summary.glm will