Better Health With More Friends: The Role of Social Capital in Producing Health
利用美国青少年健康纵向调查数据，估计朋友数量对个人健康的影响，发现多一个朋友可使总体健康指标提高6.6%标准差，并改善身心健康和减少吸烟频率。
This paper estimates the effect of an individual's number of friends on own health outcomes. The identification strategy exploits the panel structure of the friendship data from the National Longitudinal Study of Adolescent Health to estimate individual fixed effects in the likelihood of friendship formation and then uses the fixed effect estimates as a control function in a model relating health outcomes to number of friends. Empirical results show that having a larger number of friends improves physical and mental health and also lowers the frequency of smoking cigarettes. Specifically, making one more friend increases an individual's general health measure by 6.6% of a standard deviation. This suggests that accumulating social capital through friendship interactions is beneficial to health.