[R] cross-validation for count data

[Brian Ripley]

On Wed, 15 Nov 2006, valerio.orioli at libero.it wrote:

> I'm trying to use cross-validation (cv.glm) for count data. Does someone 
> know which is the appropriate cost function for Poisson distribution?

It depends on the scientific problem, not the distribution.
You could use the deviance but it may well not be appropriate for your 
context, so please seek statistical advice.

BTW, this is off-topic (see the posting guide) which is why your previous

https://stat.ethz.ch/pipermail/r-help/2006-November/116948.html

went unanswered.  Please don't clog the list with repeats like this.

And cv.glm is part of package boot (I presume) which you did not mention 
and if so is support software for a book that may help you ....

> Thank you in advance.
>
> Valerio.
> Conservation Biology Unit
> Department of Environmental and Territory Sciences
> University of Milano-Bicocca
> Piazza della Scienza,1
> 20126 Milano, Italy.

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>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595