Abstract: Exploratory data analysis has become more important as large rich data sets become available, with many explanatory variables representing competing theoretical constructs. The restrictive assumptions of linearity and additivity of effects as in regression are no longer necessary to save degrees of freedom. Where there is a clear criterion (dependent) variable or classification, sequential binary segmentation (tree) programs are being used. We explain why, using the current enhanced version (SEARCH) of the original Automatic Interaction Detector program as an illustration. Even the simple example uncovers an interaction that might well have been missed with the usual multivariate regression. We then suggest some promising uses and provide one simple example.