Efficient Kidney Exchange : Coincidence of Wants in Markets with Compatibility-Based Preferences

Patients 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 quot;double coincidence of wants.quot; Developing infrastructure to perform 3-way as well as 2-way exchanges will have a substantial effect on the number of transplants that can be arranged. Larger than 3-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