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Overview of the Correspondence Analysis

The Correspondence analysis performs simple correspondence analysis, which you can use to analyze frequency data and associations between two or more
nominal variables. The correspondence analysis finds a low-dimensional representation of the rows and columns of a contingency
table consisting of the counts for the variables.

While principal component analysis constructs directions in the space of variables that explain variance, correspondence analysis
constructs directions (sometimes called *principal coordinates*) that explain *inertia*. Inertia is the total chi-square statistic divided by the total number of observations. Correspondence analysis computes directions
that best explain deviations from expected values (assuming no association). The analysis graphically represents each row
and column by a point in a *configuration plot*.

You can run the Correspondence analysis by selecting → → from the main menu. The analysis is implemented by calling the CORRESP procedure in SAS/STAT software. See the documentation
for the CORRESP procedure in the
*SAS/STAT User's Guide* for additional details. For a general introduction to correspondence analysis, see Friendly (2000).