Abstract
We experimentally study the Gale and Shapley (1962) mechanism, utilized in a wide set of applications, most prominently the National Resident Matching Program (NRMP). Several insights come out of our analysis: First, only 48% of our observed outcomes are stable. Among those, a large majority culminates at the receivers-optimal stable matching. Second, receivers rarely truncate their true preferences; it is the proposers who do not make offers in order of their preference, frequently skipping potential partners. Third, market characteristics affect behavior: both the cardinal representation and core size influence whether laboratory outcomes arestable. We conclude by using our controlled results to shed light on a number of stylized facts we derive from new NRMP survey and outcome data, and to explain the small cores previously documented for the NRMP.