Roth, AlvinSönmez, TayfunÜnver, M. Utku2009-02-062007Roth, Alvin E., Tayfun Sönmez and M. Utku Ünver. 2007. Efficient Kidney Exchange: Coincidence of Wants in a Markets with Compatibility-Based Preferences. American Economic Review 97(3): 828-851.0002-8282http://nrs.harvard.edu/urn-3:HUL.InstRepos:2562809Patients needing kidney transplants may have donors who cannot donate to them because of blood or tissue incompatibility. Incompatible patient-donor pairs can exchange donor kidneys with other pairs only when there is a “double coincidence of wants.” Developing infrastructure to perform three-way as well as two-way exchanges will have a substantial effect on the number of transplants that can be arranged. Larger than three-way exchanges have less impact on efficiency. In a general model of type-compatible exchanges, the size of the largest exchanges required to achieve efficiency equals the number of types.10.1257/aer.97.3.828