ECON Seminar / Battal Doğan (University of Bristol)

Matching with Weak Preferences: Redesigning Teacher Assignment in Italy
 

Centralized assignment systems often require participants to submit strict rankings, even when they could rank some alternatives as tied. We show how mechanisms can elicit and use such ties to improve assignments. We introduce Deferred Acceptance with Coordinated Choice, a class of mechanisms that elicit weak preferences and attain the efficiency frontier of fair and strategy-proof mechanisms in a priority-based assignment model. We apply the framework to Italy’s centralized teacher assignment system, where teachers’ rank-order lists may include both individual schools and broader geographic regions representing ties among schools. We propose a redesign that eliminates priority violations and Pareto improves over the standard simple tie-breaking benchmark. Our theoretical results, combined with administrative data, show that ties can be a source of efficiency when properly incorporated into market design.