[R] Better idea than Poisson?
Patrick Connolly
P.Connolly at hortresearch.co.nz
Fri Jan 25 04:44:08 CET 2002
My data has three factors, a discrete response and an offset column.
>From the summary of a glm object derived using three way interactions,
I get this deviance information:
(Dispersion parameter for poisson family taken to be 1)
Null deviance: 39244 on 896 degrees of freedom
Residual deviance: 11913 on 795 degrees of freedom
AIC: 13905
Number of Fisher Scoring iterations: 6
The rather high residual deviance could indicate that the data does
not fit a poisson distrubution very well. That's believable since in
quite a number of combinations of the three factors, zero occurs more
often that one might expect for a Poisson distribution.
Are there suggestions as to what might be a better way to analyse this
data?
Thanks
--
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