There are a number of techniques that help us to identify inherently different groups of records. They differ to the techniques above because they concern groups of variables within records, rather than variables across records. These are useful in segmentation and description of markets.

Correspondence Mapping
This interdependence technique produces a perceptual map describing the relationship between nominal variables, usually in two dimensions.  The distances between category points describe the relationships:  similar categories are placed close together, dissimilar categories far apart. Correspondence is a measure of association and is generally an exploratory technique.  It is useful for showing, say, both brands and respondent characteristics on one map.