The core subjects of trade theory are the pattern and volume of trade: which goods are traded by which countries, and how much of those goods are traded. The first part of this paper discusses evidence on comparative advantage, with an emphasis on carefully connecting theoretical models with...

A core prediction of the Heckscher-Ohlin theory is that countries specialize in goods in which they have a comparative advantage, and that the source of comparative advantage is differences in relative factor supplies. To examine this theory, we use the most extensive data set available and...