What matters in school choice tie-breaking? How competition guides design

• 成果类型: Article
• 署名作者: Ashlagi, Itai; Nikzad, Afshin
• 署名单位: Stanford University; University of Southern California
• 刊物名称: JOURNAL OF ECONOMIC THEORY
• ISSN/ISSBN: 0022-0531
• DOI: 10.1016/j.jet.2020.105120
• 发表日期: 2020
• 关键词: Market design; school choice; matching

摘要

Many school districts apply the student-proposing deferred acceptance algorithm after ties among students are resolved exogenously. This paper compares two common tie-breaking rules: one in which all schools use a common lottery, and one in which each school uses a separate independent lottery. We identify the balance between supply and demand as the determining factor in this comparison. We analyze a two-sided assignment model with random preferences in over-demanded and under demanded markets. In a market with a surplus of seats, a common lottery is less equitable, and there are efficiency tradeoffs between the two tie-breaking rules. However, a common lottery is always preferable when there is a shortage of seats in the sense of stochastic dominance of the rank distribution. The theory suggests that popular schools should use a common lottery to resolve ties. We run numerical experiments with New York City school choice data after partitioning the market into popular and non-popular schools. The experiments support our findings. (C) 2020 Elsevier Inc. All rights reserved.