The consistency of partitions across time

The Duplication of Purchase Law summarises an established empirical pattern that competing brands share customers in line with their market share. However, sometimes deviations from expected sharing occur, indicating a partition. Partitions are formed by a set of brands sharing more than expected with each other. This research aims to document the consistency (or lack of) for such partitions. TNS Superpanel data is used for two product categories over three years. We find that partitions in both markets are consistent across time. Partition analyses can underpin market structure strategy decisions as a result. Refereed/Peer-reviewed