[R] Compare lm() to glm(family=poisson)

[Ken Knoblauch]

Mark Na <mtb954 <at> gmail.com> writes:
> 
> Dear R-helpers,
> I would like to compare the fit of two models, one of which I fit using lm()
> and the other using glm(family=poisson). The latter doesn't provide
> r-squared, so I wonder how to go about comparing these
> models (they have the same formula).
> 
> Thanks very much,
> 
> Mark Na
> 
I'm not sure what you are trying to do but it might be
informative to compare the diagnostic plots from the
fits.  Remember that Poisson distributed data is
heteroscedastic, mean = variance, which isn't the
default hypothesis when fitting with lm.  Also, the
default link function with the poisson family is log.
So, these are things to take into account in any potential 
comparison.  

Ken

-- 
Ken Knoblauch
Inserm U846
Stem-cell and Brain Research Institute
Department of Integrative Neurosciences
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