[Rd] Estimating overdispersion when using glm for count and binomial data

[Ben Bolker]

David Fletcher <dfletcher <at> maths.otago.ac.nz> writes:

> 
> Dear All
> 
> I recently proposed a simple modification to Wedderburn's 1974 estimate 
> of overdispersion for count and binomial data, which is used in glm for 
> the quasipoisson and quasibinomial families (see the reference below).
> 

 [snip]

> 
> The modification is very simple and would take at most a couple of 
> lines of code. The reference below gives details regarding its 
> asymptotic properties, as well as simulation results that illustrate the 
> benefits of using it for sparse data.
> 
  [snip]

> 
> D.J. Fletcher (2012) Estimating overdispersion when fitting a 
> generalized linear model to sparse data. Biometrika 99:230–237 
> (http://biomet.oxfordjournals.org/content/99/1/230.abstract?etoc)

  This looks really useful.  Base R is very conservative; despite the
fact that it would be much more easily adopted in base R, I think it
is much more likely to find a home in an add-on package such as aods3
or glm2 than in base R ...

  cheers
    Ben Bolker