Graphical Insight and Data Analysis for the 2,2,2 Crossover Design
S-Plus code is presented for the graphical insight into, and the statistical analysis of, a two-treatment, two-period, two-treatment-sequence, or 2,2,2 crossover design. In this introductory section, we describe the 2,2,2 crossover design and its uses in the pharmaceutical industry with emphasis on food interaction studies. We also introduce a specific example and a dataset which will be used pedagogically throughout the chapter. In Section 7.2, we provide a brief introduction to data management in S-Plus demonstrating just enough manipulations to facilitate the graphical methods and data analyses which follow. Section 7.3 presents a series of graphs for the initial exploration and discovery stage of the analysis of the 2,2,2 crossover design. In Section 7.4, we perform the usual normal theory ANOVA and provide a clear and decision-oriented summary and inference plot. Section 7.5 presents several graphical tools for the “visualization of the ANOVA” and a subsequent model fit assessment, and we end with a summary in Section 7.6.
KeywordsModel Check Sequence Effect Treatment Sequence Crossover Design Data Frame
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- Agresti (1990). Analysis of Categorical Data. Wiley, New York.Google Scholar
- Bradstreet, T.E. (1992). Favorite data sets from early phases of drug research—Part 2. Proceedings of the Section on Statistical Education. American Statistical Association, pp. 219–223.Google Scholar
- Chambers, J.M., Cleveland, W.S., Kleiner, B., and Tukey, P.A. (1983). Graphical Methods for Data Analysis. Wadsworth, Pacific Grove, CA.Google Scholar
- Cleveland, W.S. (1993). Visualizing Data. Hobart Press, Summit, NJ.Google Scholar
- Jones, B. and Kenward, M.G. (1989). Design and Analysis of Crossover Trials. Chapman Hall, London.Google Scholar
- Semi, S. (1993). Cross—over Trials in Clinical Research. Wiley, New York.Google Scholar
- Tukey, J.W. (1977). Exploratory Data Analysis. Addison—Wesley, Reading, MA.Google Scholar
- Venables, W.N. and Ripley, B.D. (1999). Modern Data Analysis. Third Edition. Springer—Verlag, New York.Google Scholar