In Fall 2009, officials from Chicago Public Schools abandoned 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 them re-submit 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 our 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. Our
approach provides support for these and other recent policy changes involving allocation
mechanisms.National Science Foundation (U.S.