Contrasting Split Plot and Repeated Measures Experiments and Analyses

Abstract

The terms “split plot” and “repeated measures” are used by many authors throughout the statistical literature. However, the former is not used in a consistent manner, since many authors use this term in reference to inherently different experimental situations, each requiring a different analysis. Conversely, quite often inherently different experiments share a common analysis, as is the case with some types of split-plot and repeated measures experiments. Four distinct analyses are employed by various authors when describing split plot and repeated measures experiments in the classic literature. Four linear models, accounting for the four analyses, are stated in this article. Detailed examples are given that illustrate the relationships between experimental setup, model specification, and subsequent analysis.

Key Words:

• Hypothesis testing
• Sum of squares
• Experimental design
• Linear model
• Covariance