INVESTIGATING PURCHASE INCIDENCE, BRAND CHOICE AND PURCHASE QUANTITY DECISIONS OF HOUSEHOLDS

We develop a comprehensive utility maximizing framework to study the impact of marketing variables on the category purchase, brand choice and purchase quantity decisions of households for frequently purchased packaged goods. The model allows for dependence among the three decisions while ensuring that these decisions provide, in combination, the greatest possible utility to the household. By accounting for variations in reservation prices and intrinsic brand preferences across households, the modeling framework explicitly captures the effects of unobserved heterogeneity on all three purchase decisions. The principal empirical finding from analyzing the A. C. Nielsen data for the yogurt product category is that the substantive implications for the effects of marketing variables are sensitive to whether these effects are determined conditional or unconditional on a product category purchase. Our results show that reservation prices and intrinsic brand preferences vary across households, and not accounting for these variations in the estimation could lead to biased estimates for the coefficients of the marketing variables. A comparison of our results to those obtained from a nested logit model of purchase incidence and brand choice reveals that our proposed model performs better using both a formal statistical test as well as the criterion of predictive validity in a holdout sample of panelists. Further, the purchase quantity model compares favorably with two alternative models of quantity choice in the validation sample.