P__disp function

A function to calculate Pearson Chi2 and its dispersion statistic following glm and glm.nb.

This function calculates Pearson Chi2 statistic and the Pearson-based dipersion statistic. Values of the dispersion greater than 1 indicate model overdispersion. Values under 1 indicate under-dispersion.

P__disp(x)

Arguments

• x: the fitted model.

Returns

• pearson.chi2: Pearson Chi2 value.

• dispersion: Pearson-basde dispersion.

Details

To be used following glm and glm.nb functions.

Author(s)

Joseph Hilbe and Andrew Robinson

References

Hilbe, J.M., and Robinson, A.P. 2013. Methods of Statistical Model Estimation. Chapman & Hall / CRC.

See Also

glm, glm.nb

Examples

data(medpar)
mymod <- glm(los ~ hmo + white + factor(type), 
             family = poisson, 
             data = medpar)
P__disp(mymod)