Marketing managers make decisions about price, advertising, promotion, and other marketing variables on the basis of factual data, judgments, and assumptions about how the market works. BRANDAID is a flexible, on-line model for assembling these elements to describe the market and evaluate strategies. this paper motivates the model and presents its mathematics. The structure is modular so that ... [Show full abstract] individual decision areas can be added or deleted at will. The model is of the aggregate response type, in which decision variables relate closely to specific sales performance measures. The major submodels are advertising, promotion, price, salesmen, and retail distribution.