Hierarchical versus other market share models for markets with many items

Understanding the competition between products constitutes an important problem area in marketing. The existence of many items in a product category requires that researchers consider placing restrictions on the nature of competition in consumer response models. However, little is known about the relative appropriateness of alternative model specifications that differ in constraints. We propose hierarchical models, and we compare different possible hierarchies against each other and against recently developed nonhierarchical specifications. We discuss how the alternative specifications accommodate asymmetry in competition, We also show analytical linkages between the different models, and we provide a preliminary empirical comparison of these models based on aggregate (market-level) scanner data. (C) 1997 Elsevier Science B.V.