The Substitutability of Brands

Ehrenberg (1988, for example) has shown that comparatively few purchasers of a product category are 100% loyal to a particular brand. Most consumers show multi-brand purchasing over a sequence of shopping opportunities, choosing within a small “repertoire” of available brands. Ehrenberg explains this in terms of the functional similarities of brands within a product category. Usually, they have near-identical physical formulations and perform identical tasks. The consumer typically exchanges one brand for another because the benefits gained from one are directly substitutable with those provided by others within the repertoire. Ehrenberg is equally known for his approach to theory formulation, resolutely opposing premature theory-building, and favoring instead the detailed observation of buyer behavior and the empirical determination of patterns within the data, especially recurrences of brand choice regularities. Theory can, and should, come later (Ehrenberg, 1993). However, Ehrenberg’s assumptions about, and explanations of, the patterns he identifies can be evaluated only if there is a theoretical account of consumer choice that elucidates the meaning of his findings. His work, and that of his colleagues, collaborators and other researchers, spans several decades: it is surely time to move on now to the theory-building phase of this research program.