Consumption Risk-Sharing in Social Networks
建立模型，将个体间的联系视为社会抵押品以执行非正式保险支付，发现网络扩张性（以人均连接数衡量）决定保险程度，二维网络（如秘鲁村庄）能实现良好风险分担，且次优安排下保险是局部的。
We develop a model in which connections between individuals serve as social collateral to enforce informal insurance payments. We show that: (i) The degree of insurance is governed by the expansiveness of the network, measured with the per capita number of connections that groups have with the rest of the community. “Two-dimensional” networks—like real-world networks in Peruvian villages—are sufficiently expansive to allow very good risk-sharing. (ii) In second-best arrangements, insurance is local: agents fully share shocks within, but imperfectly between endogenously emerging risk-sharing groups. We also discuss how endogenous social collateral affects our results.