Dear list members,
I am fitting a negative binomial model but I get a very large dispersion
parameter. Why is that?
quine.nb2 <- glm.nb(Pt ~ Agua + Dist10, data = Abundancia)
summary(quine.nb2)
Deviance Residuals:
Min 1Q Median 3Q Max
-2.20911 -0.67157 0.04411 0.35695 1.65524
Coefficients:
Estimate Std. Error z value Pr(>|z|)
(Intercept) -0.88354 0.43982 -2.009 0.0445 *
Agua[T.negra] 0.89319 0.43727 2.043 0.0411 *
Dist10 0.39416 0.04387 8.984 <2e-16 ***
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
(Dispersion parameter for Negative Binomial(67552.88) family taken to be 1)
Null deviance: 128.567 on 15 degrees of freedom
Residual deviance: 17.005 on 13 degrees of freedom
AIC: 67.058
Number of Fisher Scoring iterations: 1
Theta: 67553
Std. Err.: 1428117
Warning while fitting theta: iteration limit reached
2 x log-likelihood: -59.058
Best,
Manuel
--
*Manuel Spínola, Ph.D.*
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspin...@una.ac.cr
mspinol...@gmail.com
Teléfono: (506) 2277-3598
Fax: (506) 2237-7036
Personal website: Lobito de río <https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
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