Product differentiation and foreign trade in CGE models of small economies

In recent years, two classes of computable general equilibrium (CGE) trade models have been used to investigate external sector policies: single country and and multicountry trade models. The authors examine the treatment of exports and imports in recent single country CGE models of small economies. They present a simple, one sector analytical model that captures the major features of the multi sector counterpart used in applied models. They show that applying the same assumption about product differentiation to imports as to exports gives rise to a well behaved, price taking economy and normally shaped offer curves. They illustrate the one-sector model with a numerical example which shows the implications of the choice of weights used as a proxy for the domestic price index in computations of real exchange rate indices. The model also shows the role of foreign trade elasticities in the popular Australian model, with traded and nontraded goods. Trade substitution elasticities on the import side play a crucial role in determining the direction of change in real exchange rate during terms of trade perturbations.