20.1 Absolute and Comparative Advantage

International trade is built on the principles of absolute and comparative advantage. These concepts explain why countries specialize in producing certain goods and services, even when they're not the best at making everything.

Comparative advantage, based on opportunity costs, is the real driver of trade. When countries focus on what they produce at the lowest relative cost, total output goes up. This specialization leads to increased efficiency and economic gains for all trading partners.

Absolute and Comparative Advantage

Absolute vs comparative advantage

Absolute advantage occurs when a country can produce a good using fewer resources (labor, capital, land) than another country. For example, if the US can produce 1,000 cars with the same resources China uses to produce 800 cars, the US has an absolute advantage in car production. This is a straightforward comparison: who makes more with less?

Comparative advantage is different and more powerful. It occurs when a country has a lower opportunity cost of producing a good compared to another country. Opportunity cost here means the amount of one good that must be given up to produce an additional unit of another good.

Here's where it gets interesting: a country can have a comparative advantage in a good even if another country has the absolute advantage in producing it. If the opportunity cost of producing one car in the US is 2 computers, but in China it's 3 computers, the US has the comparative advantage in cars. China would then have the comparative advantage in computers, because it gives up fewer cars per computer produced. Comparative advantage is shaped by a country's factor endowments, such as natural resources, labor supply, and technology.

Specialization and trade gains

When countries specialize in producing goods for which they have a comparative advantage, total output rises even though the same resources are being used. Countries then trade with each other to get the goods they don't produce domestically.

The key result: specialization and trade allow both countries to consume beyond what they could produce on their own. This is what economists call gains from trade.

• If the US specializes in aircraft (its comparative advantage) and China specializes in electronics (its comparative advantage), the combined output of both goods will be higher than if each country tried to produce both.
• The US trades some aircraft to China in exchange for electronics, and both countries end up with more of both goods than they'd have without trade.
• Resources get allocated to their most productive uses, which is what economists mean by production efficiency.

Opportunity costs in comparative advantage

To find comparative advantage, you need to calculate opportunity costs. Here's the process:

1. For each country, divide the amount of the good given up by the amount of the other good produced.
2. Compare the opportunity costs across countries.
3. The country with the lower opportunity cost for a given good has the comparative advantage in that good.

Worked example: Suppose the US can produce either 1,000 cars or 5,000 computers, and Japan can produce either 800 cars or 6,000 computers.

1. US opportunity cost of one car: $\frac{5{,}000 \text{ computers}}{1{,}000 \text{ cars}} = 5$ computers per car
2. Japan opportunity cost of one car: $\frac{6{,}000 \text{ computers}}{800 \text{ cars}} = 7.5$ computers per car
3. The US has the lower opportunity cost ($5 < 7.5$), so the US has a comparative advantage in car production.
4. Now flip it. US opportunity cost of one computer: $\frac{1}{5} = 0.2$ cars. Japan opportunity cost of one computer: $\frac{1}{7.5} \approx 0.133$ cars. Since $0.133 < 0.2$, Japan has the comparative advantage in computers.

Notice that Japan actually produces more computers in absolute terms (6,000 vs. 5,000), so Japan has the absolute advantage in computers. But the point is that even if one country has an absolute advantage in both goods, both countries still benefit from specializing according to comparative advantage and trading.

International Trade and Economic Interdependence

• Specialization based on comparative advantage leads to increased trade between countries.
• The terms of trade determine the relative prices at which goods are exchanged. For trade to benefit both sides, the terms of trade must fall between the two countries' opportunity costs. In the example above, a trade price between 5 and 7.5 computers per car would make both the US and Japan better off.
• As countries trade more, they become economically interdependent, relying on each other for goods and services they no longer produce domestically.