Editing Comparative advantage (section)

==Haberler's opportunity costs formulation==
In 1930 Austrian-American economist [[Gottfried Haberler]] detached the doctrine of comparative advantage from Ricardo's labor theory of value and provided a modern opportunity cost formulation. Haberler's reformulation of comparative advantage revolutionized the theory of international trade and laid the conceptual groundwork of modern trade theories.

Haberler's innovation was to reformulate the theory of comparative advantage such that the value of good X is measured in terms of the forgone units of production of good Y rather than the labor units necessary to produce good X, as in the Ricardian formulation. Haberler implemented this opportunity-cost formulation of comparative advantage by introducing the concept of a production possibility curve into international trade theory.{{sfn|Bernhofen|2005a|pages=997–1000}}