[R-sig-eco] Possion model for paired data

Peter Solymos solymos at ualberta.ca
Fri Mar 6 17:13:54 CET 2009

Hi Manuel,

I would suggest to use the signed difference. This will be Skellam
distribution with expected value mu1-mu2 (means of the two Poisson
distr) and variance mu1+mu2. The skellam and vglm functions in the
VGAM package can be used for a likelihood ratio test for equal means
(see example(skellam)). Please let me know if this works, because I
haven't tried yet.



Péter Sólymos, PhD
Postdoctoral Fellow
Department of Mathematical and Statistical Sciences
University of Alberta
Edmonton, Alberta, T6G 2G1
email <- paste("solymos", "ualberta.ca", sep = "@")

On Fri, Mar 6, 2009 at 7:00 AM, Manuel Spínola <mspinola10 at gmail.com> wrote:
> Dear list memebers,
> Is there a way to do a paired t test but using a poisson model (for counts).
> Thank you very much in advance.
> Best,
> Manuel Spínola
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