Inefficiency-Manipulability Tradeoff in the Parallel Mechanism

19 Pages Posted: 3 Jun 2019 Last revised: 23 Oct 2019

See all articles by Jerry Anunrojwong

Jerry Anunrojwong

Columbia University - Columbia Business School

Date Written: October 23, 2019


Most school choice and other matching mechanisms are based on deferred acceptance (DA) for its incentive properties. However, non-strategyproof mechanisms can dominate DA in welfare because manipulation in preference rankings can reflect the intensities of underlying cardinal preferences. In this work, we use the parallel mechanism of Chen and Kesten, which interpolates between Boston mechanism and DA, to quantify this tradeoff. While it is previously known that mechanisms that are closer to Boston mechanism are more manipulable, we show that they are also more efficient in student welfare if school priorities are weak. Our theoretical results show the inefficiency-manipulability tradeoff in the worst case, while our simulation results show the same tradeoff in the typical case.

Keywords: school choice, matching markets, parallel mechanism, approximate Pareto efficiency, tie-breaking

JEL Classification: C78

Suggested Citation

Anunrojwong, Jerry, Inefficiency-Manipulability Tradeoff in the Parallel Mechanism (October 23, 2019). Available at SSRN: or

Jerry Anunrojwong (Contact Author)

Columbia University - Columbia Business School ( email )

3022 Broadway
New York, NY 10027
United States


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