Oct 22, 2015 Filed in: Working papers
With S. Nageeb Ali and Yilin David Yang
Abstract: In a multilateral enforcement regime, a player who cheats on one partner is punished by many partners. But if partners can renegotiate in private, they can subvert the power of the multilateral punishment. We introduce a new notion of “bilateral renegotiation proofness” that applies to multilateral games with private monitoring. We show that while players’ ability to renegotiate bilaterally is socially costly, it is perhaps not as costly as one might expect. We study a single seller interacting with many buyers, as well as communities in which everyone interacts with everyone else. In both cases, as the number of participants grows, the proportional cost imposed by bilateral renegotiation declines, and vanishes in the limit.
Working paper 10/22/2015
Jul 07, 2015 Filed in: Working papers
With S. Nageeb Ali
Abstract: Many communities rely upon ostracism to enforce cooperation: if an individual shirks in one relationship, her innocent neighbors share information about her guilt in order to shun her, while continuing to cooperate among themselves. However, a strategic victim may herself prefer to shirk, rather than report others' deviations truthfully. If guilty players are to be permanently ostracized, then such deviations are so tempting that cooperation in any relationship is bounded by what the partners could obtain through bilateral enforcement. We show that ostracism can improve upon bilateral enforcement if it is tempered by forgiveness, through which guilty players are eventually readmitted to cooperative society.
Major update: Working paper 7/7/2015
Jan 10, 2015 Filed in: Publications
With Kareen Rozen
Published in The American Economic Journal: Microeconomics, 6(4):326–361, November 2014
Abstract: We study optimal contracting in team settings where agents have many opportunities to shirk, task-level monitoring is needed to provide useful incentives, and it is difficult to write individual performance into formal contracts. Incentives are provided informally, using wasteful sanctions like guilt and shame, or slowed promotion. These features give rise to optimal contracts with underperformance, forgiving sanctioning schemes, and endogenous supervision structures. Agents optimally take on more assigned tasks than they intend to complete, leading to the concentration of supervisory responsibility in the hands of one or two agents.
Published article (restricted access)
Published article and Supplementary Appendix (free access)
Nov 13, 2013 Filed in: Publications
With Joel Watson
Published in Econometrica, 81(6):2303–2350, November 2013.
Abstract: This paper proposes a new approach to equilibrium selection in repeated games with transfers, supposing that in each period the players bargain over how to play. Although the bargaining phase is cheap talk (following a generalized alternating-offer protocol), sharp predictions arise from three axioms. Two axioms allow the players to meaningfully discuss whether to deviate from their plan; the third embodies a “theory of disagreement”—that play under disagreement should not vary with the manner in which bargaining broke down. Equilibria that satisfy these axioms exist for all discount factors and are simple to construct; all equilibria generate the same welfare. Optimal play under agreement generally requires suboptimal play under disagreement. Whether patient players attain efficiency depends on both the stage game and the bargaining protocol. The theory extends naturally to games with imperfect public monitoring and heterogeneous discount factors, and yields new insights into classic relational contracting questions.
Feb 06, 2013 Filed in: News
I am leaving UCSD to join the Economics Department
at the University of Michigan
, effective July 1, 2013. I will miss my San Diego colleagues very much, but I’m excited to work with the faculty and students at Michigan.
Jul 10, 2012 Filed in: News
For the 2012–2013 school year, I am visiting Microsoft Research New England
. I’m looking forward to lots of productive interactions with the permanent researchers, postdocs, and other visitors!
Apr 01, 2012 Filed in: Publications
Published in The Review of Economic Studies, 79(2):778–811, April 2012.
Abstract: The game-theoretic literature on collusion has been hard pressed to explain why a cartel should engage in price wars, without resorting to either impatience, symmetry restrictions, inability to communicate, or failure to optimize. This paper introduces a new explanation that relies on none of these assumptions: if the cartel's member firms have private information about their costs, price wars can be optimal in the face of complexity. Specifically, equilibria that are robust to payoff-irrelevant disruptions of the information environment generically cannot attain or approximate efficiency. An optimal robust equilibrium must allocate market shares inefficiently, and may call for price wars under certain conditions. For a two-firm cartel, cost interdependence is a sufficient condition for price wars to arise in an optimal robust equilibrium. That optimal equilibria are inefficient generically applies not only to collusion games, but also to the entire separable payoff environment (Chung & Ely 2006)—a class that includes most typical economic models.
Published article (free access)