R-Squared measures for count data regression models with applications to health-care utilization

AC Cameron*, Frank Windmeijer

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

216 Citations (Scopus)


R-squared measures of goodness of fit for count data are rarely, if ever, reported in empirical studies or by statistical packages. We propose several R-squared measures based on various definitions of residuals for the basic Poisson regression model and for more general models such as negative binomial that accommodate overdispersed data The preferred R-squared measure is based on the deviance residual. An application to data on health-care-service utilization measured in counts illustrates the performance and usefulness of the various R-squared measures.

Original languageEnglish
Pages (from-to)209-220
Number of pages12
JournalJournal of business & economic statistics
Issue number2
Publication statusPublished - Apr 1996


  • deviance
  • deviance residual
  • goodness of fit
  • negative binomial regression
  • Pearson residual
  • Poisson regression
  • FIT

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