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

poisGOF(obj)

Arguments

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

## 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)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(DAMisc)
Loading required package: car
Loading required package: effects

Attaching package: 'effects'

The following object is masked from 'package:car':

    Prestige

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/DAMisc/poisGOF.Rd_%03d_medium.png", width=480, height=480)
> ### Name: poisGOF
> ### Title: Deviance and Chi-squared Goodness-of-Fit Test for Poisson Models
> ### Aliases: poisGOF
> 
> ### ** Examples
> 
> ## 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))
  treatment outcome counts
1         1       1     18
2         1       2     17
3         1       3     15
4         2       1     20
5         2       2     10
6         2       3     20
7         3       1     25
8         3       2     13
9         3       3     12
> glm.D93 <- glm(counts ~ outcome + treatment, family=poisson())
> poisGOF(glm.D93)
             Stat p-value
Chi-squared 5.173   0.270
Deviance    5.129   0.274
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>