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School Admissions Reform in Chicago and England: Comparing Mechanisms by their Vulnerability to Manipulation

Are Parents Gaming their School Assignment?

School Assignment, January 2011

In a study of school admis­sions sys­tems, Parag Pathak and Tayfun Sonmez intro­duce a method to com­pare the mech­a­nisms which dis­tricts use to assign stu­dents to seats based on their vul­ner­a­bil­ity to manip­u­la­tion and offer insight into dis­trict pol­icy changes in case stud­ies of Chicago Public Schools’ aban­don­ment of their old assign­ment mech­a­nism in 2009 and England’s nation­wide ban on the pop­u­lar Boston mech­a­nism in 2007.


Recent admis­sions reforms have been based in part on the desire to sim­plify the strate­gic aspects of the admis­sions process for par­tic­i­pants.  However, unlike admis­sions reforms in Boston and New York City, changes to how stu­dents are matched to seats in Chicago and England did not involve the direct inter­ven­tion of econ­o­mists.  As a result, these changes pro­vide some indi­ca­tion of how pol­i­cy­mak­ers and the pub­lic per­ceive par­tic­u­lar meth­ods of stu­dent assign­ment.  In par­tic­u­lar, offi­cials from Chicago Public Schools changed their assign­ment mech­a­nism for cov­eted spots at selec­tive col­lege prepara­tory high schools mid­stream. After ask­ing about 14,000 appli­cants to sub­mit their pref­er­ences for schools under one mech­a­nism, the dis­trict asked they re-submit their pref­er­ences under a new mech­a­nism. Officials were con­cerned that “high-scoring kids were being rejected sim­ply because of the order in which they listed their col­lege prep pref­er­ences” under the aban­doned mech­a­nism. What is some­what puz­zling is that the new mech­a­nism is also manip­u­la­ble. This paper intro­duces a method to com­pare mech­a­nisms based on their vul­ner­a­bil­ity to manip­u­la­tion. Under this notion, the old mech­a­nism is more manip­u­la­ble than the new Chicago mech­a­nism. Indeed, the old Chicago mech­a­nism is at least as manip­u­la­ble as any other plau­si­ble mech­a­nism. A num­ber of sim­i­lar tran­si­tions between mech­a­nisms took place in England after the widely pop­u­lar Boston mech­a­nism was ruled ille­gal in 2007. The study’s approach pro­vides sup­port for these and other recent pol­icy changes involv­ing the way chil­dren obtain school seats.