International trade and comparative advantage: WACE Year 12 Economics Unit 3

What this dot point is asking

SCSA wants you to explain the theoretical case for international trade. You must distinguish absolute advantage from comparative advantage, use opportunity cost to identify who should specialise in what, and show the mutual gains. Expect this as a multiple choice item, a short calculation, or part of an extended response on why Australia trades.

Absolute advantage

A country has an absolute advantage in a good when it can produce more of it from the same resources, or the same amount using fewer resources, than another country. Absolute advantage explains some trade but not all of it. If one country were better at producing everything, absolute advantage alone would suggest no trade should occur. The theory of comparative advantage, developed by David Ricardo, shows trade still benefits both.

Comparative advantage and opportunity cost

A country has a comparative advantage in a good when it can produce it at a lower opportunity cost than another country. Opportunity cost is the value of the next best alternative given up.

Worked numerical example. Suppose with one unit of resources Australia can produce either 6 tonnes of wheat or 3 units of cloth, while Country B can produce either 2 tonnes of wheat or 2 units of cloth.

• Australia has an absolute advantage in both goods (6 > 2 wheat, 3 > 2 cloth).
• Australia's opportunity cost of 1 wheat is $\tfrac{3}{6} = 0.5$ cloth. Country B's is $\tfrac{2}{2} = 1$ cloth.
• Australia's opportunity cost of 1 cloth is $\tfrac{6}{3} = 2$ wheat. Country B's is $\tfrac{2}{2} = 1$ wheat.

Australia gives up less cloth to make wheat (0.5 vs 1), so Australia has the comparative advantage in wheat. Country B gives up less wheat to make cloth (1 vs 2), so Country B has the comparative advantage in cloth. Each should specialise accordingly.

The gains from specialisation and trade

The gains arise because specialisation pushes each country to its most efficient use of resources, and trade lets each consume a combination outside its own production possibility frontier (PPF). Diagrammatically, the consumption point sits beyond the country's PPF after trade, which is impossible without trade.

The terms of trade range

For trade to benefit both, the agreed exchange rate (the terms of trade in this two-good sense) must lie between the two countries' opportunity cost ratios. In the example, the price of 1 wheat must be between 0.5 cloth (Australia's domestic cost) and 1 cloth (Country B's domestic cost). Outside that range one country would prefer to produce the good itself.

Applying it to Australia

Australia's comparative advantage lies in resource and energy commodities (iron ore, coal, LNG, gold) and some agriculture (wheat, beef, wool), reflecting abundant land and mineral endowments. It imports manufactured goods, machinery and consumer electronics, where economies of scale and capital concentration give trading partners such as China the lower opportunity cost. ABS trade data consistently show minerals and fuels making up well over half of Australia's goods exports, which is exactly what comparative advantage predicts for a land-and-resource-rich, capital-scarce economy.

Limitations of the simple model

The textbook model assumes constant opportunity costs, no transport costs, two goods and two countries, and full factor mobility within (but not between) countries. In reality opportunity costs rise as resources are reallocated, transport and tariffs matter, and adjustment imposes structural unemployment on shrinking industries. These limitations do not overturn the gains-from-trade conclusion but explain why governments still intervene.