# Deviance and Chi-squared Goodness-of-Fit Test for Poisson Models

### Description

Deviance and Chi-squared goodness-of-fit test of the null hypothesis that poisson variance is appropriate to model the conditional dispersion of the data, given a particular model.

### Usage

1 | ```
poisGOF(obj)
``` |

### Arguments

`obj` |
A model object of class |

### Value

A 2x2 data frame with rows representing the different types of statistics (Deviance and Chi-squared) and columns representing the test statistic and p-value.

### Author(s)

Dave Armstrong (UW-Milwaukee, Department of Political Science)

### References

Dobson, A. J. (1990) An Introduction to Generalized Linear Models. London: Chapman and Hall.

### Examples

1 2 3 4 5 6 7 8 | ```
## Example taken from MASS help file for glm, identified to be
## Dobson (1990) Page 93: Randomized Controlled Trial :
counts <- c(18,17,15,20,10,20,25,13,12)
outcome <- gl(3,1,9)
treatment <- gl(3,3)
print(d.AD <- data.frame(treatment, outcome, counts))
glm.D93 <- glm(counts ~ outcome + treatment, family=poisson())
poisGOF(glm.D93)
``` |