Deviations from Matching in Consumer Choice

Consumer researchers have established that most buyers of fast-moving consumer goods such as packaged foods practice multi-brand purchas-ing. Analyses of such products show that most consumers tend to purchase a variety of brands within a product category, selecting among a small “repertoire ” of brands rather than being exclusively loyal to a single brand (Ehrenberg, 1988). Research generally shows that in stationary conditions (i.e., the absence of any marked short-term trend in sales) only a few consumers acquire a given brand on consecutive shopping occasions; (b) most consumers buy several different brands, selecting them apparently randomly from a subset or ‘repertoire ’ of known, tried and tested brands. At the brand level, (c) each brand attracts only a small percentage of 100%-loyal consumers; (d) brands within a product category tend to differ broadly with respect to their penetration levels but tend to be more similar in terms of their av-erage purchasing frequency; and (e) brands with smaller penetration levels (or market shares) also tend to show smaller average buying frequencies and smaller percentages of 100%-loyal consum-ers (i.e., the effect known as “Double Jeopardy”). These patterns have been demonstrated for a vari-ety of product categories, from food and drinks to aviation fuel, from personal care products to phar-maceutical prescriptions, for patterns of shopping trips and selection of store chains (Ehrenberg