Trade, opportunity cost and the distribution of gains

Learning goals

• Explain comparative advantage using opportunity costs rather than productivity alone.
• Analyze trade restrictions and distinguish stages of economic integration.

Draft · approximately 45 minutes, excluding further revision.

A productivity lead is not the whole trade argument

Absolute advantage concerns output per input. Comparative advantage concerns what must be forgone to produce one more unit of a good. Even a country that is more productive in both goods can gain by specializing according to relative opportunity costs and trading at a mutually acceptable price. These are model results under stated resources and adjustment assumptions, not a claim that every person gains equally.

Trade can expand available consumption, competition and scale, while workers and capital in exposed sectors face adjustment costs. Distribution, mobility, institutions and transition support affect the experience. A national net gain can coexist with concentrated losses. Evaluate the time horizon and counterfactual rather than treating “trade is beneficial” as evidence that no one bears a cost.

Restrictions change prices and who receives rents

For a small price-taking importing economy, a tariff can raise the domestic import price, benefit protected producers, reduce consumer surplus and collect revenue. Deadweight loss arises from distorted production and consumption. A quota restricts quantity and creates rents whose recipient depends on allocation and ownership of import rights. An export subsidy can support exporters while imposing fiscal costs and distorting resource allocation. Retaliation and terms-of-trade effects require additional assumptions.

A free-trade area removes selected internal barriers while members retain separate external policies. A customs union adds a common external tariff; a common market adds freer factor movement; deeper economic union coordinates further policies. Trade creation replaces higher-cost domestic production; trade diversion can replace a lower-cost nonmember supplier with a higher-cost member. Membership alone does not prove a welfare gain in every case.

Formula and assumptions

Opportunity cost of X = forgone Y / additional X; tariff-inclusive price = world price × (1+tariff) under full pass-through

Two countries and two goods

1. Per hour, A produces either 6 cloth or 2 wine; B produces either 4 cloth or 4 wine. A’s opportunity cost of 1 cloth is 1/3 wine; B’s is 1 wine.
2. A has comparative advantage in cloth; B in wine. A price of 1 cloth for 0.5 wine lies between the two opportunity costs and can support gains for both under the model.
3. Separately, an assumed 10% tariff on a world import price 100 makes the tariff-inclusive price 110 if fully passed through. Real pass-through and welfare effects need demand, supply and market assumptions.

Errors to catch

• Confusing absolute productivity with comparative opportunity cost.
• Treating national gains as equally distributed or assuming quota rents always go to government.

Original knowledge check

Answer every question before checking. Review explanations after submitting; retry starts a new attempt.

Sources and coverage status

These original lessons are drafts. Public outlines are used to check scope; the official learning-outcome text and proprietary question banks are not reproduced here. Follow the source for exam-year requirements and updates.

• Reference · www.cfainstitute.org
• Reference · www.wto.org