Designs to reduce the error


  • Blocking
  • Analysis of covariance

Learning objectives

At the end of the session, students should be capable of

  • explain the benefits of blocked design and ANCOVA over completely randomized designs
  • using control covariates or blocking factors
  • testing equality of slopes


Complementary readings

  • Chapter 9 of Maxwell et al. (2017).
  • Chapter 4 of Cox (1958).



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Cox, D. R. (1958). Planning of experiments. Wiley.
Maxwell, S. E., Delaney, H. D., & Kelley, K. (2017). Designing experiments and analyzing data: A model comparison perspective (3rd ed.). routledge.
Meier, L. (2022). ANOVA and mixed models: A short introduction using R (Chapman & Hall/CRC, Eds.).