12. Analysis of Covariance

  1. Michael J. Crawley

Published Online: 14 SEP 2007

DOI: 10.1002/9780470515075.ch12

The R Book

The R Book

How to Cite

Crawley, M. J. (2007) Analysis of Covariance, in The R Book, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470515075.ch12

Author Information

  1. Imperial College London at Silwood Park, UK

Publication History

  1. Published Online: 14 SEP 2007
  2. Published Print: 20 APR 2007

ISBN Information

Print ISBN: 9780470510247

Online ISBN: 9780470515075



  • Analysis of covariance (ANCOVA);
  • model simplification and analysis of covariance;
  • calculating standard errors;
  • intercept of regression for grazed treatment;
  • ANCOVA and experimental design;
  • treatment contrasts;
  • Helmert contrasts in hypothesis testing


This chapter contains sections titled:

  • Analysis of Covariance in R

  • ANCOVA and Experimental Design

  • A More Complex ANCOVA: Two Factors and One Continuous Covariate

  • Contrasts and the Parameters of ANCOVA Models

  • Order matters in summary.aov