We derive a small open economy (SOE) as the limit of an economy as the number or size of its trading partners goes to infinity and trade costs also go to infinity. We obtain this limit in the Armington, Eaton-Kortum, Krugman, and Melitz models. In all cases, the trade of the SOE with the foreign...

This paper argues that the theoretical foundations for the gravity equation are general, while the empirical performance of the gravity equation is specific to the type of goods examined. Most existing theory for the gravity equation depends on the assumption of differentiated goods. We show...

The elasticity of substitution between goods from different countries---the Armington elasticity---is important for many questions in international economics, but its magnitude is subject to debate: the "macro" elasticity between home and import goods is often found to be smaller than the...

The elasticity of substitution between goods from different countries---the Armington elasticity---is important for many questions in international economics, but its magnitude is subject to debate: the "macro" elasticity between home and import goods is often found to be smaller than the...