[R-sig-eco] Question about poisson GLM

[rosanna di maggio]

Dear all,

I'm trying to perform a poisson GLM with lme4 using the number of
individuals as dependent variable and i) years of study and ii) different
study areas as factors... So far so good..

But the results are quite curious...  The estimates and standard errors are
huge.. Is is normal? I don't think so...


This is an example of what happen:


Call:
glm(formula = NTOT ~ areaN * anno, family = poisson)

Deviance Residuals:
    Min       1Q   Median       3Q      Max
-3.7465  -1.0629  -0.5000   0.3132   6.8188

Coefficients:
              Estimate Std. Error z value Pr(>|z|)
(Intercept) 140.786646  27.766187   5.070 3.97e-07 ***
areaN        71.479294  11.876992   6.018 1.76e-09 ***
anno         -0.069199   0.013823  -5.006 5.56e-07 ***
areaN:anno   -0.035572   0.005912  -6.017 1.78e-09 ***




I cannot understand the reason of these results... Someone can help me?



Thank you

Rox

-- 
Rosanna Di Maggio,PhD student,
Laboratorio di Zoogeografia ed Ecologia Animale (LABZEA)
Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Famaceutiche
(STEBICEF)
Universita'  di  Palermo, Via Archirafi 18 - 90123 Palermo (I)
Mobile: +393290842994
Email 2: rosanna.dimaggio01@ <rosannadimaggio at gmail.com>unipa.it
Website: www.researchgate.net/profile/Rosanna_Di_Maggio?ev=prf_highl

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