The Gravity Equation in International Trade

This chapter offers a selective survey of the gravity equation (GE) in international trade. This equation started in the Sixties as a purely empirical proposition to explain bilateral trade flows, without little or no theoretical underpinnings. At the end of the Seventies, the GE was "legitimized" by a series of theoretical articles that demonstrated that the basic GE form was consistent with various models of trade flows. Empirical applications of GE expanded to cover a variety of issues, such as the impact of regional trade agreements, national borders and currency unions on trade, as well as the use of the equation to sort out the relative merit of alternative trade theories. A new wave of studies is now concentrating on the general equilibrium properties of the GE and finer econometrics points. The renewed interest of the academic profession in the development of the GE is undoubtedly driven by the equation's empirical success