Abstract
We study the school choice problem and propose a new criterion for comparing non-strategy-proof mechanisms: robustness to manipulations. Mechanism A is more robust than mechanism B if each student (given any preferences of this student and any profile of schools’ priorities) can potentially access a smaller set of schools via a profitable manipulation under mechanism A than under mechanism B. This criterion strengthens the two independent criteria proposed by Bonkoungou and Nesterov (Theor Econ 16(3):881–909, 2021) and Decerf and Van der Linden (J Econ Theory 197:105313, 2021). We then show that all results obtained with these two criteria, as well as with the original criterion proposed by Pathak and Sönmez (Am Econ Rev 103(1):80–106, 2013), can also be obtained using robustness. Our results provide a stronger rationalization for a wide range of reforms in school choice and college admissions system.