Product differentiation, firm heterogeneity and international trade: Exploring the Alchian–Allen effect

In a model of international trade with horizontally differentiated goods, increasing returns and monopolistically competitive markets, this paper proposes that the degree of differentiation in a product mix–defined as the ratio of the number of varieties to the total value of imports–can be regarded as another aspect of quality. Furthermore, this paper draws a parallel to the Alchian–Allen effect and shows that, when firms are heterogeneous in either fixed or variable costs, the degree of differentiation is increasing in per unit transportation costs.