Free riding and participation in large scale, multi-hospital kidney exchange
研究了大型多医院肾脏交换中医院只登记难匹配患者而内部处理易匹配患者的搭便车行为，发现保证医院完全参与的成本在大多数情况下很低，但若不保证则可能损失大量移植机会，并提出一种高效且激励医院披露所有患者-捐赠者对的机制。
As multi-hospital kidney exchange has grown, the set of players has grown from patients and surgeons to include hospitals. Hospitals can enroll only their hard-tomatch patient-donor pairs, while conducting easily-arranged exchanges internally. This behavior has already been observed. We show that the cost of making it individually rational for hospitals to participate fully is low in almost every large exchange pool (although the worst-case cost is very high), while the cost of failing to guarantee individual rationality could be high, in lost transplants. We identify a mechanism that achieves high efficiency while giving hospitals incentives to reveal all patient-donor pairs. 1