Analysis of two consecutive purchase records, easily collected from a simple survey, has
been shown to reveal many of the well-known brand buying patterns found in consumer
panel data (Bennett, 2003a, 2008; Bennett, Ehrenberg, & Goodhardt, 2000). The
technique, although still relatively new, is useful in markets where full datasets are hard to
come by, or where a diagnostic test is required quickly. In this paper we extend the
technique from frequently purchased stable categories to two conditions suggested in
Bennett et al. (2000), an infrequently bought item in a dynamic market context.