Our study seeks to identify the social contagion of in-group gifts: if gifts trigger their recipients to send more gifts subsequently, the actual impact of a gift on group dynamics would be greatly amplified. Causal identification of contagion is always challenging in observational data; To identify gift contagion, we leverage a natural experiment using a large sample of 36 million online red packets sent within 174,131 chat groups on WeChat, one of the largest social network services worldwide. Our natural experiment is enabled by WeChat's random gift amount algorithm, with which the amount that a user receives does not depend on her own attributes. We find that, on average, receiving one more dollar causes a recipient to send 18 cents back to the group within the subsequent 24 hours. Moreover, this effect is much stronger for "luckiest draw" recipients or those who receive the largest share from a red packet, suggesting a group norm according to which the luckiest draw recipients should send the first subsequent red packets. Additionally, we find that gift contagion is affected by in-group friendship network properties, such as the number of in-group friends and the local clustering coefficient.
翻译:我们的研究试图确定群体内礼品的社会传染:如果礼品的接受者后来会送更多的礼品,那么礼品对群体动态的实际影响就会大大扩大。 观察数据总是难以确定传染的缘故; 为了查明礼品传染,我们利用全世界最大的社交网络服务之一WeChat 上的174,131个聊天小组内发送的3 600万个在线红包的大量样本来进行自然实验。我们的自然实验是由WeChat的随机礼品数量算法促成的,用户收到的数量并不取决于她自己的属性。我们发现,平均而言,如果收到1美元,接受者就会在24小时内将18美分送回群体。此外,对于“最幸运的提款”的接受者或从红包中获得最大份额的接受者来说,这种效果要大得多,这表明最幸运的受款者应该发送随后的第一个红包的团体规范。此外,我们发现礼品传染受集团内友谊网络特性的影响,例如集团内朋友的数目和当地组合系数。