Time-constrained Dynamic Mechanisms for College Admissions

Recent literature shows that dynamic matching mechanisms may outperform their static counterparts. The college admissions procedure used in Inner Mongolia motivates an underexplored design dimension of such mechanisms: the time constraint that students face. We study the time-constrained dynamic mechanism (TCDM) theoretically and show that, under straightforward behavior, it can generate unstable outcomes and, in some cases, outcomes that are Pareto dominated by those produced by the student-proposing deferred acceptance mechanism (DA). We also compare students' assignment probabilities under TCDM and DA. Under this behavior, TCDM gives each student a weakly higher probability of receiving her first choice. Under universal acceptability and sufficient aggregate capacity, it also gives each student a weakly higher probability of remaining unassigned and a weakly lower probability of receiving a non-first-choice college.