Editing Stolper–Samuelson theorem (section)

==History==
It was derived in 1941 from within the framework of the [[Heckscher–Ohlin model]] by [[Wolfgang Stolper]] and [[Paul Samuelson]],<ref>{{Cite journal  |last1=Stolper |first1=W. F. |last2=Samuelson |first2=Paul A. | author-link1 = Wolfgang Stolper | author-link2 = Paul Samuelson | title = Protection and real wages | journal = [[The Review of Economic Studies]] | volume = 9 | issue = 1 | pages = 58–73 | doi = 10.2307/2967638 | jstor = 2967638 | date = November 1941 |s2cid=153734773 }}</ref> but has subsequently been derived in less restricted models. As a term, it is applied to all cases where the effect is seen. [[Ronald W. Jones]] and [[José Scheinkman]] show that under very general conditions the factor returns change with output prices as predicted by the theorem.<ref>{{Cite journal  |last1=Jones |first1=Ronald W. |last2=Scheinkman |first2=Jose A. | author-link1 = Ronald W. Jones |  author-link2 = Jose Scheinkman | title = The relevance of the two-sector production model in trade theory | journal = [[The Journal of Political Economy]] |volume=85 |issue=5 |pages=909–935 | jstor = 1830339 | date = 1977 |doi=10.1086/260615 }}</ref> If considering the change in real returns under increased [[international trade]] a robust finding of the theorem is that returns to the scarce factor will go down, [[ceteris paribus]]. An additional robust corollary of the theorem is that a [[Payment|compensation]] to the scarce factor exists which will overcome this effect and make increased trade [[Pareto optimal]].<ref name=neary>{{cite book | last = Neary | first = J. Peter | author-link = J. Peter Neary | title = The Stolper–Samuelson theorem | url = http://users.ox.ac.uk/~econ0211/papers/pdf/stolpers.pdf | publisher = [[Centre for Economic Policy Research]] | location = London | year = 2004 }}</ref>
The original [[Heckscher–Ohlin model]] was a two-factor model with a labor market specified by a single number. Therefore, the early versions of the theorem could make no predictions about the effect on the unskilled labor force in a high-income country under trade liberalization. However, more sophisticated models with multiple classes of worker productivity have been shown to produce the Stolper–Samuelson effect within each class of labor: Unskilled workers producing traded goods in a high-skill country will be worse off as international trade increases, because, relative to the world market in the good they produce, an unskilled [[first world]] production-line worker is a less abundant factor of production than capital.

The Stolper–Samuelson theorem is closely linked to the [[factor price equalization theorem]], which states that, regardless of international factor mobility, factor prices will tend to equalize across countries that do not differ in technology.