Two further impossibility results on responsive affirmative action in school choice

Abstract

This paper investigates the responsiveness of priority-based affirmative action in school choice. We consider two efficiency-improved mechanisms—Kesten’s EADAM (efficiency-adjusted deferred acceptance mechanism) and DA-TTC mechanism (running deferred acceptance and then running top trading cycles algorithm). We show that neither EADAM nor DA-TTC is minimally responsive to the priority-based affirmative action policy. That is, under EADAM or DA-TTC, there are market situations in which a stronger affirmative action policy may result in a Pareto inferior assignment for the minority students.