INCOME IN THE GRAVITY MODEL OF BILATERAL TRADE: Does Endogeneity Matter?

This paper addresses the possible endogeneity of income in the gravity model by providing instrumental variables for income. Using these instruments (physical capital, human capital, and labor accumulation rates) in regression equations of the gravity model, it is shown that the effect of income on bilateral trade is highly significant and, in some cases, is not appreciably different from ordinary least squares estimates. The impact on trade of other gravity variables, including dummy variables for membership in various trading blocs, is also examined.