14. Count Data

  1. Michael J. Crawley

Published Online: 6 NOV 2012

DOI: 10.1002/9781118448908.ch14

The R Book, Second Edition

The R Book, Second Edition

How to Cite

Crawley, M. J. (2012) Count Data, in The R Book, Second Edition, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781118448908.ch14

Author Information

  1. Imperial College London at Silwood Park, UK

Publication History

  1. Published Online: 6 NOV 2012
  2. Published Print: 7 DEC 2012

ISBN Information

Print ISBN: 9780470973929

Online ISBN: 9781118448908



  • count data, collected by scientists, statisticians as counts;
  • regression with Poisson errors;
  • Poisson errors, residual deviance equal to residual degrees of freedom;
  • analysis of deviance with count data;
  • analysis of covariance with count data;
  • frequency distributions, and Poisson process;
  • good candidate distribution, as negative binomial distribution;
  • log-linear models, and overdispersion;
  • negative binomial errors, using a negative binomial model


This chapter contains sections titled:

  • A regression with Poisson errors

  • Analysis of deviance with count data

  • Analysis of covariance with count data

  • Frequency distributions

  • Overdispersion in log-linear models

  • Negative binomial errors