In this paper we concentrate on the explicit relation between models and market data. In order to formulate the subset of data to be stored in the date, bank three rather simple mathematical models are developed, namely: 1. A response model to explain the fluctuation in the demand for a certain product (primary demand); 2. Response model to explain the fluctuations in the selective demand, for a certain brand; 3. A policy model, this means a set of relations which supplement the response relations in order to evaluate the effects of a number of global decision alternatives.