School Choice with Consent: An Experiment

Public school choice often yields student assignments that are neither fair nor efficient. The efficiency-adjusted deferred acceptance mechanism (EADAM) allows students to consent to waive priorities that have no effect on their assignments. A burgeoning recent literature places EADAM at the centre of the trade-off between efficiency and fairness in school choice. Meanwhile, the Flemish Ministry of Education has taken the first steps to implement this algorithm in Belgium. We provide the first experimental evidence on the performance of EADAM against the celebrated deferred acceptance mechanism (DA). We find that both efficiency and truth-telling rates are higher under EADAM than under DA, even though EADAM is not strategy-proof. When the priority waiver is enforced, efficiency further increases, while truth-telling rates decrease relative to the EADAM variants where students can dodge the waiver. Our results challenge the importance of strategy-proofness as a prerequisite for truth-telling and portend a new trade-off between efficiency and vulnerability to preference manipulation.