[R] How do I set the dispersion parameter in poisson glm?

Ben Bolker bbolker at gmail.com
Thu Oct 7 21:03:52 CEST 2010


Huso, Manuela <manuela.huso <at> oregonstate.edu> writes:

> 
> Thank you so much for your reply, Z.  Of course, you are correct about
>  the overdispersion not affecting
> parameter estimation.  But my goal is comparison of several models 
> using QAIC and the dispersion
> parameter enters the QAIC calculation.  I suppose I could calculate 
> the QAIC of all models using my fixed
> dispersion parameter, but I was hoping I could just set it in the 
> glm call and let the software calculate
> QAIC appropriately for me.

  [snip]

   Which QAIC() function are you using?
  The ones in the MuMIn,AICcmodavg, and bbmle packages all
have parameters that should allow you to set the dispersion
parameter when you calculate QAIC.



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