The marketing of goods is a case of innovation diffusion and has been treated as such [ I , 3, 4, 5, 6, 7, 81. Marketing is an effort to get people to purchase a good, and sales of that good can be looked on as a measure of adoption. There are two basic approaches to marketing diffusion theory: an aspatial approach and a spatial approach. The goal of this paper is to present both views, m.d to show how they can be integrated into a single theory. The results are quite rich, in that they indicate the relationship between marketing budgets, price of goods, intensity of advertising, the rate of interest, and the spatial distribution of marketing policies.
THE ASPATIAL VIEWAdvertising theorists have taken the view that profits are a function of the following: selling price P; demand at time t, x(t); the cost of inducing that demand C(.); and the interest rate r. Demand is generated in two ways: through advertising at any given time u( t), and through retirement; i.e., the rate k at which previous consumers must replace the product. From a communica-