poisgof {epicalc} | R Documentation |
Poisson and negative binomial regression are used for modeling count data. The command tests the deviance against degrees of freedom in the model determining whether there is overdispersion.
poisgof (model)
model |
A Poisson or negative binomial model |
To test the significance of overdispersion of the errors of a Poisson or negative binomial model, the deviance is test against degrees of freedom using chi-squared distribution. A low P value indicates significant overdispersion.
Virasakdi Chongsuvivatwong <cvirasak@medicine.psu.ac.th>
`glm'
library(MASS) quine.pois <- glm(Days ~ Sex/(Age + Eth*Lrn), data = quine, family=poisson) poisgof(quine.pois) quine.nb1 <- glm.nb(Days ~ Sex/(Age + Eth*Lrn), data = quine) poisgof(quine.nb1)