Strategy-proofness in the Large

Strategy-proofness in the Large

Coauthors: Eduardo M Azevedo
Review of Economic Studies, (2019): 86, no. 1, 81-116. [PDF]


We propose a criterion of approximate incentive compatibility, strategy-proofness in the large (SP-L), and argue that it is a useful second-best to exact strategy-proofness (SP) for market design. Conceptually, SP-L requires that an agent who regards a mechanism’s “prices” as exogenous to her report—be they traditional prices as in an auction mechanism, or price-like statistics in an assignment or matching mechanism—has a dominant strategy to report truthfully. Mathematically, SP-L weakens SP in two ways: (1) truth-telling is required to be approximately optimal (within epsilon in a large enough market) rather than exactly optimal, and (2) incentive compatibility is evaluated ex interim, with respect to all full-support i.i.d. probability distributions of play, rather than ex post with respect to all possible realizations of play. This places SP-L in between the traditional notion of approximate SP, which evaluates incentives to manipulate ex post and as a result is too strong to obtain our main results in support of SP-L, and the traditional notion of approximate Bayes-Nash incentive compatibility, which, like SP-L, evaluates incentives to manipulate ex interim, but which imposes common knowledge and strategic sophistication assumptions that are often viewed as unrealistic.


Appendix, Strategy Proofness in the Large


Earlier Version

2016 Working Paper Version

with Eduardo M. Azevedo..
[PDF] [All Related Material]


ACM EC Panel Discussion Slides (June 2018)


Seminar Slides (Nov 2012)

University of Pennsylvania Theory Seminar, November 2012. [PDF]