The Small Open Economy in a Generalized Gravity Model

To provide sharp answers to basic questions in international trade, a standard approach is to focus on a small open economy (SOE). Whereas the classic tradition is to define a SOE as an economy that takes world prices as given, in the modern trade literature a SOE is defined instead as one that takes foreign-good prices and export demand schedules as given. In this paper we develop a generalized gravity model that nests all of its standard microfoundations (e.g., Armington and Melitz-Pareto) and show how to take the limit so that an economy that becomes infinitesimally small behaves like a SOE. We then show how the resulting model of a SOE can be used to understand comparative statics and the optimal tariff in a way that is robust across the different microfoundations consistent with the gravity model.Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.