ECONOMIC INSTRUCTION Choosing Partners: A Classroom Experiment

In standard models of economic choice, consumers select their favorite commodity bundles from among those that they can afford. Nobody asks the chosen commodities how they feel about the consumers who choose them. Students, however, are familiar with real-life decision problems in which the outcomes depend crucially on the preferences of both the choosers and the chosen. The so-called “marriage problem” is a classic example. Consider a population of men and women who seek partners of the opposite sex. Each person has a personal ranking of possible partners. These rankings may be similar or wildly different among individuals. Clearly, it is unlikely that partners can be assigned in such a way that everyone gets their first choice. What can we expect to happen in a “market” where partnerships must be formed by mutual consent? This problem is posed in a beautiful article by David Gale and Lloyd Shapley, “College Admissions and the Stability of Marriage” (1962). Gale and Shapley define a stable marriage assignment as a matching of partners such that no two persons of opposite sex prefer each other to their assigned partners. This seems a reasonable requirement for stability, because if two individuals discover that they prefer each other to their current partners, we might expect them to abandon their partners and run off together. Gale and Shapley show that if each participant has a strict preference ordering (no ties) over members of the opposite sex, then there always must