22 Krugman/Obstfeld/Melitz • International Economics: Theory & Policy, Tenth Edition
intensive in the factors with which they are abundantly supplied. Trade has strong effects on the relative
earnings of resources and, according to theory, leads to equalization across countries of factor prices.
These theoretical results and related empirical findings are presented in this chapter.
The chapter begins by developing a general equilibrium model of an economy with two goods that are
each produced using two factors according to fixed coefficient production functions. The assumption of
fixed coefficient production functions provides an unambiguous ranking of goods in terms of factor
intensities. (A more realistic model allowing for substitution between factors of production is presented
later in the chapter with the same conclusions.) Two important results are derived using this model. The
first is known as the Rybczynski effect. Increasing the relative supply of one factor, holding relative goods
prices constant, leads to a biased expansion of production possibilities favoring the relative supply of the
good that uses that factor intensively.
The second key result is known as the Stolper-Samuelson effect. Increasing the relative price of a good,
holding factor supplies constant, increases the return to the factor used intensively in the production of
that good by more than the price increase, while lowering the return to the other factor. This result has
important income distribution implications.
It can be quite instructive to think of the effects of demographic/labor force changes on the supply of
different products. For example, how might the pattern of production during the productive years of the
“Baby Boom” generation differ from the pattern of production for post–Baby Boom generations? What
does this imply for returns to factors and relative price behavior? What effect would a more restrictive
immigration policy have on the pattern of production and trade for the United States?
The central message concerning trade patterns of the Heckscher-Ohlin theory is that countries tend to
export goods whose production is intensive in factors with which they are relatively abundantly endowed.
Comparing the United States and Mexico, for example, we observe a relative abundance of capital in the
United States and a relative abundance of labor in Mexico. Thus, goods that intensively use capital in
production should be cheaper to produce in the United States, and those that intensively use labor should
be cheaper to produce in Mexico. With trade, the United States should export capital-intensive goods like
computers, while Mexico should export labor-intensive goods like textiles. With integrated markets,
international trade should lead to a convergence of goods prices. Thus, the prices of capital-intensive
After presenting the basic theory behind the Heckscher-Ohlin theory, the rest of the chapter examines empirical
tests of the model, beginning with a pair of case studies looking at income inequality in the United States.
Wages paid to skilled workers in the United States have been rising at a much faster rate than those paid to
unskilled workers over the past few decades. At the same time, there has been a large increase in
international trade. Given that the United States is relatively abundant in skilled labor, the Heckscher-