Median Polish

Median polish finds an additive fit to data in a two-way table:
observed value = grand mean + row term + column term + residual.

To properly analyze and understand results of median polish, you should be familiar with the following terms and concepts:

• outliers
• location
• spread
• residuals
• resistance
• robustness
• heavy-tailedness
• light-tailedness
• skewness
• transformation
• interaction
• two-way layout

If you are not familiar with these terms and concepts, you are advised to consult with a statistician. Failure to understand and properly apply median polish may result in drawing erroneous conclusions from your data. Additionally, you may want to consult the following references:

• Hoaglin, D. C., Mosteller, F., and Tukey, J. W. (eds.). 1983. Understanding Robust and Exploratory Data Analysis. New York: John Wiley & Sons.
• Hoaglin, D. C., Mosteller, F., and Tukey, J. W. (eds.). 1985. Exploring Data Tables, Trends, and Shapes. New York: John Wiley & Sons.
• Mosteller, F. and Tukey, J. W. 1977. Data Analysis and Regression. Cambridge, MA: Addison-Wesley.
• Tukey, J. W. 1977. Exploratory Data Analysis. Cambridge, MA: Addison-Wesley.
• Velleman, P. F. and Hoaglin, D. C. 1981. Applications, Basics, and Computing of Exploratory Data Analysis. Duxbury Press.

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