Use opportunity cost ratios and a production possibility analysis to demonstrate how two countries both gain from specialising and trading, and explain the limits and distribution of those gains

What this dot point is asking

SCSA wants you to move beyond simply defining comparative advantage. You must be able to calculate opportunity cost ratios from a numerical table, identify who specialises in what, set out the range of mutually beneficial trade prices, and prove with numbers that both countries end up better off. Expect a data table and a short calculation task.

From comparative advantage to actual gains

Comparative advantage tells you who should specialise. The gains from trade show how much better off both parties become once they do. The key idea is opportunity cost: the value of the next best alternative forgone when resources are used to make one good rather than another.

Working a numerical example

Suppose, using one unit of resources, Australia can produce 10 tonnes of wheat or 5 tonnes of wool, while New Zealand can produce 4 tonnes of wheat or 4 tonnes of wool.

• In Australia, 1 tonne of wheat costs 0.5 tonnes of wool (5 divided by 10).
• In New Zealand, 1 tonne of wheat costs 1 tonne of wool (4 divided by 4).

Australia gives up less wool to make wheat, so Australia has the comparative advantage in wheat. By the reverse logic, New Zealand has the comparative advantage in wool (1 tonne of wool costs only 1 tonne of wheat in NZ, but 2 tonnes of wheat in Australia).

The range of mutually beneficial prices

Trade is only worthwhile if the international exchange rate of the two goods falls between the two countries' domestic opportunity cost ratios. Outside that range, one country would do better producing the good itself.

In the example, the price of wheat must lie between 0.5 and 1 tonne of wool. At exactly 0.5 it gives Australia no gain; at exactly 1 it gives New Zealand no gain. Anywhere in between splits the gains, with the exact split decided by relative bargaining power and world demand and supply.

Why Australia trades the way it does

This model explains the real composition of Australian trade. Australia has a strong comparative advantage in resource-intensive and land-intensive goods (iron ore, coal, LNG, wheat, beef) because it is resource and land abundant. It imports manufactured goods and consumer electronics where partners such as China have the lower opportunity cost. Specialising along these lines, rather than protecting uncompetitive manufacturing, is the efficiency argument for an open economy.

The model also has limits worth noting in evaluation. It assumes resources move freely between industries, ignores transport costs and the time needed to retrain workers, and says nothing about how the gains are distributed within a country. Workers in an import-competing industry can lose even when the nation as a whole gains.