What is Intra-Industry Trade?
Comparative advantage, however, at least at first glance, does not seem especially well-suited to explain other common patterns of international trade.
The theory of comparative advantage suggests that trade should happen between economies with large differences in opportunity costs of production.
Roughly half of all world trade involves shipping goods between the fairly similar high-income economies of the United States, Canada, the European Union, Japan, Mexico, and China.
Moreover, the theory of comparative advantage suggests that each economy should specialize to a degree in certain products, and then exchange those products.
A high proportion of trade, however, is intra-industry trade—that is, trade of goods within the same industry from one country to another.
For example, the United States produces and exports autos and imports autos. In all of these categories, the United States is both a substantial exporter and a substantial importer of goods from the same industry.
Why do similar high-income economies engage in intra-industry trade? What can be the economic benefit of having workers of fairly similar skills making cars, computers, machinery and other products which are then shipped across the oceans to and from the United States, the European Union, and Japan?
There are two reasons: (1) The division of labor leads to learning, innovation, and unique skills; and (2) economies of scale.
Comparative Advantage and Intra-Industry Trading
The sources of gains from intra-industry trade between similar economies—namely, the learning that comes from a high degree of specialization and splitting up the value chain and from economies of scale—do not contradict the earlier theory of comparative advantage. Instead, they help to broaden the concept.
In intra-industry trade, climate or geography do not determine the level of worker productivity. Even the general level of education or skill does not determine it. Instead, how firms engage in specific learning about specialized products, including taking advantage of economies of scale determine the level of worker productivity.
In this vision, comparative advantage can be dynamic—that is, it can evolve and change over time as one develops new skills and as manufacturers split the value chain in new ways.
This line of thinking also suggests that countries are not destined to have the same comparative advantage forever, but must instead be flexible in response to ongoing changes in comparative advantage.