Smart Lotteries in School Choice: Ex-ante Pareto-Improvement with Ex-post Stability
New algorithm promises better school matches for students without sacrificing stability.
Deep Dive
Researchers propose a 'smart lottery' mechanism to improve school choice systems. It enhances the standard Deferred Acceptance algorithm by optimizing lottery outcomes, providing a Pareto-improvement in expected welfare while maintaining ex-post stability. Although computationally NP-hard, it's solvable via integer programming. Tests on real and generated data show substantially larger welfare gains compared to standard post-lottery optimization methods, meaning students get better expected school placements without disrupting system fairness.
Why It Matters
This could make high-stakes school admissions more efficient and fair for millions of families globally.