A Projection Pursuit Method on the Multidimensional Squared Contingency Table

In this study a projection pursuit method in used to explore e^d (square) contingency table data. The method operates on projection matrices constructed from the contingency tables using affine geometry and creates projections (or marginals) using a Radon transform. The projection matrices and the projections can be used to find the "interesting" (nonuniform structure), and to cluster and to order the cases. This projection pursuit method is implemented with graph visualization of projection. It is similar to the discrete version of Andrews' curve. We demonstrate how this approach compares to association rules commonly used in data mining using a market basket data set and compare the PP results with the analysis of a data set from Wishart and Leach (1970).