Regional Integration and Trade: Controlling for Varying Degrees of Heterogeneity in the Gravity Model

The proliferation of regional trade agreements (RTAs) in the 1990s prompted a renewal of interest in studying the effect of regional integration on trade. Using a panel dataset of bilateral export flows from 12 EU countries to 20 OECD trading partners over the period 1992-2003, the trade effect of European regional integration, denoted by an EU dummy, is examined across a number of fixed effects (FE) specifications, each of which has been claimed as the correct econometric specification of the gravity model. Typically parsimonious in (time-varying) economic variables and abundant in fixed effects, the FE specifications allow for varying degrees of heterogeneity in the gravity model. Two gravity models are estimated: a gravity model of traditional trade determinants and a gravity model of new trade theory (NTT) determinants. Both gravity models provide reasonable coefficient estimates, although they vary somewhat across the FE specifications for the traditional gravity model. Both gravity models are congruent in suggesting that the coefficient of the EU dummy declines in magnitude and becomes insignificant as an increasing degree of heterogeneity is admitted into the model. This suggests the fundamental importance of the econometric specification when evaluating trade policy effects within a gravity framework.