23. ANCOVA for Randomized-Block Designs

  1. Bradley E. Huitema

Published Online: 14 OCT 2011

DOI: 10.1002/9781118067475.ch23

The Analysis of Covariance and Alternatives: Statistical Methods for Experiments, Quasi-Experiments, and Single-Case Studies, Second Edition

The Analysis of Covariance and Alternatives: Statistical Methods for Experiments, Quasi-Experiments, and Single-Case Studies, Second Edition

How to Cite

Huitema, B. E. (2011) ANCOVA for Randomized-Block Designs, in The Analysis of Covariance and Alternatives: Statistical Methods for Experiments, Quasi-Experiments, and Single-Case Studies, Second Edition, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118067475.ch23

Author Information

  1. Department of Psychology, Western Michigan University, Kalamazoo, Michigan, USA

Publication History

  1. Published Online: 14 OCT 2011
  2. Published Print: 14 OCT 2011

Book Series:

  1. Wiley Series in Probability and Statistics

Book Series Editors:

  1. Walter A. Shewhart and
  2. Samuel S. Wilks

ISBN Information

Print ISBN: 9780471748960

Online ISBN: 9781118067475

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Keywords:

  • analysis of covariance (ANCOVA);
  • block formation;
  • conventional design;
  • randomized-block (RB) designs

Summary

The typical way of characterizing the comparison of analysis of covariance (ANCOVA) with “blocking” confounds two issues that should be kept separate: design and analysis. The actual comparison that should be articulated is the analysis of the randomized-group design using ANCOVA versus the analysis of the randomized-block design using randomized-block (RB) ANOVA. The failure to distinguish the design from the analysis has led most researchers believe that ANCOVA does not apply to the RB design. This chapter demonstrates that it is desirable to analyze the typical RB design using either (1) conventional ANCOVA or (2) a more complex analysis that includes a covariate. An approach, described as a combined ANCOVA and block analysis is recommended for the case where one variable is used for block formation and a second variable is used as a covariate.

Controlled Vocabulary Terms

analysis of covariance; randomized block design