Manipulability in School Choice

Abstract

We compare the manipulability of school choice mechanisms based on the occurrence of dominant strategies. We characterize dominant strategies in the constrained versions of the deferred acceptance (DA) and Boston (BOS) mechanisms. We leverage our characterizations to show that dominant strategies occur more often in constrained DA than in constrained BOS and that these differences can be quantitatively sizable. Dominant strategies also become more frequent in constrained DA as students are allowed to report more schools. Although our focus is on constrained mechanisms, we provide dominant strategies comparisons for other mechanisms as well, including application-rejection mechanisms and mechanisms that Pareto dominate DA.

Keywords: School choice, Dominant strategy, Undominated strategy, Manipulability, Stability, Tie-breaking, Boston mechanism, Deferred acceptance mechanism.

JEL Classification: C78, D47, D82, I 20