Heckscher-Ohlin Model vs Rybczynski Theorem
Heckscher-Ohlin Model and Rybczynski Theorem are two International & Development Economics concepts in AP Economics that students often mix up. The Heckscher-Ohlin model predicts that countries export goods that intensively use their relatively abundant factor of production and import goods using their scarce factor. The Rybczynski theorem says that, at constant prices, increasing one factor's endowment raises output of the good using it intensively more than proportionally and reduces output of the other good. Here is how they compare side by side.
Where Ricardo's comparative advantage rests on labor-productivity differences, Heckscher-Ohlin explains trade by differences in factor endowments (capital vs. labor vs. land). A capital-abundant country has comparatively cheap capital, so it specializes in and exports capital-intensive goods, while a labor-abundant country exports labor-intensive goods. The model assumes two countries, two goods, and two factors that are mobile within but not between countries.
Another pillar of the Heckscher-Ohlin model, it shows how factor growth reshapes production. If a country's capital stock grows (or it gains labor through immigration), the capital-intensive industry expands disproportionately while the labor-intensive industry actually contracts in absolute terms, holding goods prices fixed. It is used to analyze the effects of investment, immigration, and emigration on a trading economy's output mix.
Heckscher-Ohlin vs Rybczynski: Two Results From One Factor Endowments Model
| Heckscher-Ohlin model | Rybczynski theorem | |
|---|---|---|
| Question it answers | Which goods will a country export | What happens to output when a country gets more of one factor |
| What is being compared | Two countries with different endowments | One country before and after an endowment changes |
| What is held constant | Technology and tastes, so endowments do the explaining | Goods prices, so only quantities are free to respond |
| Prediction | A country exports the good that uses its abundant factor intensively | Output using the growing factor rises more than proportionally while the other good's output falls |
| Direction of the logic | From endowments to the pattern of trade | From endowments to the composition of production |
| Typical application | Why a labor abundant country exports labor intensive goods | Immigration, a capital inflow or a resource find reshaping what a country makes |
| What it does not tell you | How output responds when an endowment changes | Anything about who trades with whom |
Add 25 percent more workers and one industry shrinks outright
Work the model with numbers. An economy has 600 workers and 300 machines and makes two goods. Each unit of cloth needs 3 workers and 1 machine; each unit of steel needs 1 worker and 2 machines. Full employment means 3 times cloth plus steel equals 600, and cloth plus 2 times steel equals 300. Solving gives cloth of 180 and steel of 60, which checks out: labor used is 540 plus 60, so 600, and machines used are 180 plus 120, so 300. Now let immigration lift the workforce to 750 with machines unchanged, holding goods prices fixed so the same techniques stay profitable. The new solution is cloth of 240 and steel of 30. Labor used is 720 plus 30, so 750, and machines are 240 plus 60, so 300. Look at what moved. Labor rose 25 percent, cloth output rose 33 percent, which is more than proportionally, and steel output halved in absolute terms even though not one machine was lost. That is the Rybczynski result. Cloth can only expand by pulling machines away from steel, and with prices fixed there is no way for steel to economize on them. Read the same economy through the trade lens and it has become more labor abundant, so it exports more cloth. The unit framing both is at /macro/international-trade.
The trade prediction is a comparison, the theorem is a change
The two results get blurred because they share a setup: two goods, two factors, one technology, prices taken as given. The questions are different. Heckscher and Ohlin compare countries. An economy with plenty of workers relative to machines has a lower relative cost of labor intensive goods before trade opens, so when trade opens it exports those goods and imports the others. The pattern of trade follows from what countries have rather than from any difference in how well they produce, which is what makes the model a genuine alternative to explanations built on differing technology. Rybczynski compares nothing across borders. It takes one economy, changes the supply of a single factor, freezes the prices of goods and asks what production does. Both halves of the answer matter. The industry using the growing factor intensively expands by a larger percentage than the factor itself grew, and the other industry contracts absolutely, because the expanding one has to draw the second factor away from it. That second half is what earns the theorem its name, and it explains a pattern economists care about: why a resource boom or a large capital inflow can shrink an existing industry without that industry's own costs changing at all. The exchange rate version of the same story is at /glossary/dutch-disease.
Frequently asked questions
What is the difference between the Heckscher-Ohlin model and the Rybczynski theorem?
The Heckscher-Ohlin model predicts which goods a country exports, based on the factor it holds in relative abundance. The Rybczynski theorem instead takes one country and asks what happens to production when the supply of a factor grows, predicting that the industry using it intensively expands more than proportionally while the other industry shrinks.
Why does one industry shrink under the Rybczynski theorem?
Because factors have to come from somewhere. With goods prices fixed the production techniques do not change, so the expanding industry can only get the other factor it needs by taking it from the second industry, which therefore contracts in absolute terms even though the economy as a whole lost nothing.
Does the Heckscher-Ohlin model assume countries have different technology?
No, it assumes the same technology and similar tastes everywhere, leaving the relative supply of factors as the only difference. That is the whole point of the model: differences in endowments on their own are enough to generate trade, without either country being better at production than the other.
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