with Atila Abdulkadiroğlu, prepared for the handbook of Online and Matching-Based Market Design
Abstract. We develop a unified framework with schools and residential choices to study the welfare and distributional consequences of public schools' switching from the traditional neighborhood assignment to the Deferred Acceptance mechanism. We show that when families receive higher priorities at neighborhood schools, the Deferred Acceptance mechanism improves aggregate or average welfare compared to neighborhood assignment. Additionally, under general conditions, the Deferred Acceptance mechanism improves the welfare of lowest-income families, both with and without neighborhood priorities. Our work lays theoretical foundations for analyzing assignment games with externalities.
Abstract. We study the problem of allocating COVID-19 vaccines or other scarce and heterogeneous medical resources to patients. Our proposed solutions optimize for aggregate match-effectiveness subject to fairness and distributional constraints. The main solution uses a novel cutoff characterization result for fair and equitable allocations and a minimum-cost flow formulation. Match-effectiveness gains from optimization are substantial. Even when there are only two types of vaccines, in equal quantities, our algorithm results in more than 33% larger aggregate match-effectiveness compared to the random allocation benchmark.
with Atila Abdulkadiroğlu and Umut Dur
Abstract. Proponents of school choice argue that it improves educational outcomes by allowing parents to self-select into schools that are most effective for their children. Contrary to these arguments, empirical evidence suggests that parents may not incorporate school effectiveness or match quality when choosing schools. The findings potentially impugn proponents' effectiveness arguments of choice-based assignment. We develop novel solutions that restore effectiveness by maximizing match quality subject to stability constraints. Maximization algorithms are provided for both small and large school districts. Simulations reveal substantial match quality gains from our solutions compared to the celebrated Deferred Acceptance mechanism with a random tiebreaker. Our methodology can be used to optimize for other policy objectives in school choice or other priority-based matching problems.
with Atila Abdulkadiroğlu
Abstract. We study priority-based assignment problems with distributional and diversity objectives. Our work provides an axiomatic characterization for a general class of choice rules based on type-specific reserves and quotas. The choice rules in the class differ by the order in which applicants are considered at units reserved for different types. We show that a particular reserves- and quotas-based choice rule, where all applicants are first considered at units reserved for their own types, uniquely minimizes priority violations in this class. We discuss the implications of our results for public school choice assignment with affirmative action policies.
The paper won the Best Student Paper Prize to young researchers at the 16th European Meeting on Game Theory.
with Atila Abdulkadiroğlu
Abstract. In priority-based matching problems there is a trade-off between efficiency and reducing justified-envy. We show that minimizing justified-envy among efficient mechanisms is an NP-hard problem when objects have weak priority rankings. Consequently, we focus on resolving the trade-off in subsets of efficient mechanisms, namely, sequential dictatorships and hierarchical exchange rules. Both classes are widely studied in the literature and applied in real-life resource allocation problems. We provide polynomial-time mechanisms that minimize justified-envy in each of those classes. Additionally, we study the possibility of minimizing justified-envy in the entire classes of efficient and strategyproof mechansims. We show that none of the well-known efficient and strategyproof mechanisms, such as hierarchical exchange rules or trading cycles mechanisms minimize justified-envy in that class.
School districts commonly ration public school seats based on students preferences and priorities. Priorities reflect the school districts' objectives for reducing busing costs (walk-zone priority) or utilizing siblings' learning spillovers (sibling priority). Our work develops a simple modification of the well-studied Top Trading Cycles mechanism that matches schools to higher priority students while preserving the mechanism's desirable efficiency and incentives properties.
Equilibrium with Capacity-Constrained Firms: A Classroom Experiment
with Gayane Barseghyan, The Journal of Economic Education 50, no. 2 (2019): 129-141
Work in Progress
Matching with Complementarities, with Atila Abdulkadiroğlu
Stable Matching with Externalities
Welfare and Distributional Consequences of Public School Choice: An Empirical Analysis