from Market Design at http://bit.ly/2ikc6Hp on November 29, 2017 at 01:58PM
They find substantial welfare effects in moving from NYC’s old decentralized high school choice system (in which individual schools made uncoordinated acceptance decisions, so some students received multiple offers while others got none) to the stable matching system (using the deferred acceptance algorithm with single tie-breaking) now used. They don’t find big gains from trying to reach a student optimal stable matching by revising the tie-breaking decisions.
The Welfare Effects of Coordinated Assignment:Evidence from the New York City High School Match
By Atila Abdulkadiroglu, Nikhil Agarwal, and Parag A. Pathak
"Coordinated single-offer school assignment systems are a popular education reform. We show that uncoordinated offers in NYC’s school assignment mechanism generated mismatches. One-third of applicants were unassigned after the main round and later administratively placed at less desirable schools. We evaluate the effects of the new coordinated mechanism based on deferred acceptance using estimated student preferences. The new mechanism achieves 80 per-cent of the possible gains from a no-choice neighborhood extreme to a utilitarian benchmark. Coordinating offers dominates the effects of further algorithm modifications. Students most likely to be previously administratively assigned experienced the largest gains in welfare and subsequent achievement."
Here’s the ungated working paper