中文摘要
人际间的馈赠与借贷在高收入国家发挥着尚未得到充分研究的非正式保险作用，这对社会保险政策设计提出了挑战。我利用一套将调查数据与银行交易行政数据相链接的数据集，考察遭遇失业的美国低收入用户通过点对点（P2P）支付平台获得的非正式支持。事件研究估计显示，失业一个月后，月均P2P资金流入增加，增幅相当于损失收入的1.1%，随后在10个月内回落至基线水平。单身母亲获得的增幅最大，此前收入较高者或居住在高收入地区者亦是如此。利用联邦疫情失业保险（UI）政策的三次可合理视为外生的变动，我估计失业保险福利每增加1美元，最多挤出0.05美元的非正式转移支付。这些结果表明，失业保险可以通过在网络间分担风险来提高福利，而不会通过非正式保险削弱网络内部的风险分担。
Abstract
Interpersonal gifts and loans play an underexplored informal insurance role in high-income countries, posing challenges for social insurance policy design. I examine informal support via person-to-person (P2P) payment platforms using a survey-linked administrative bank transaction dataset covering low-income US users with job loss. Event study estimates show average monthly P2P inflows increase by 1.1 % of lost income one month after job loss before returning to baseline over 10 months. Single mothers receive the largest increases, as do those with high prior earnings or those living in high-income areas. Exploiting three plausibly exogenous changes to federal pandemic UI policy, I estimate that an additional dollar of UI benefits crowds out at most $0.05 of informal transfers. These results imply that UI can raise welfare by pooling risk across networks without reducing within-network risk pooling through informal insurance.