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Re: st: XTGEE of morbidity data


From   "Sarah A. Mustillo" <smustillo@psych.mc.duke.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: XTGEE of morbidity data
Date   Thu, 19 Jun 2003 19:12:50 -0400

Hi -

The best source of information on goodness of fit for GEE models is the Hardin & Hilbe book:

http://www.stata.com/bookstore/gee.html

Here is an excerpt from the table of contents:

4 Residuals, Diagnostics, and Testing

4.1 Criterion measures
4.1.1 Choosing the best correlation structure
4.1.2 Choosing the best subset of covariates
4.2 Analysis of residuals
4.2.1 A nonparametric test of the randomness of residuals
4.2.2 Graphical assessment
4.2.3 Quasivariance functions for PA-GEE models
4.3 Deletion diagnostics
4.3.1 Influence measures
4.3.2 Leverage measures
4.4 Goodness of fit (population-averaged models)
4.4.1 Proportional reduction in variation
4.4.2 Concordance correlation
4.4.3 A x2 goodness of fit test for PA-GEE binomial models
4.5 Testing coefficients in the PA-GEE model
4.5.1 Likelihood ratio tests
4.5.2 Wald tests
4.5.3 Score tests
4.6 Assessing the MCAR assumption of PA-GEE models
4.7 Summary 4.8 Exercises



Sarah

--On Thursday, June 19, 2003 4:20 PM -0500 Mike Sanderson <Sandersn@vet.k-state.edu> wrote:


I have a dataset of weekly morbidity counts and populations at risk from
123 pens of feedlot cattle.
Have run XTGEE family Poisson, log link, t(week) i(pen number) exp(pop
at risk)

Are there any goodness of fit statistics for this model? I have been
unable to find any. Does any one have suggestions of how to assess the
fit or a better way to deal with the data?

Thanks



Mike Sanderson DVM, MS, DACVPM, DACT
Associate Professor, Beef Production
Kansas State University, College of Veterinary Medicine
Ph: 785-532-5700,  FAX 785-532-4989
sandersn@vet.k-state.edu
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Sarah A. Mustillo, Ph.D
Department of Psychiatry and Behavioral Sciences
Duke University School of Medicine
Box 3454
Durham NC 27710

919 687-4686 x241
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*   http://www.ats.ucla.edu/stat/stata/



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