社会网络是社会资本的核心部分，对个体经济行为有着重要的影响。本项目将从一个新的视角，即通过人口政策的变化来考察社会网络如何对个体的行为产生影响。从宏观上看，人口的快速增长使得人口密度上升，人与人之间的联系更加紧密。从微观角度看，人口政策影响了家庭生育率，而家庭生育率又决定了家庭的规模和亲戚的数量，因此个体社会网络的规模和结构也受到人口政策的影响。本项目将从人口政策带来的社会网络的变化出发，研究个体创业、储蓄、家庭资产投资等经济行为如何受到影响。我们将讨论人口政策通过社会网络影响个体经济行为的理论模型和三个主要机制，即风险分担效应、放松信贷约束效应以及信息传播效应，并提出理论假设。然后使用全国范围内的微观调查数据和自己调查的有代表性村镇的社会网络详细调查数据，运用多种计量经济学模型进行实证检验。我们的研究将对我国现阶段制定人口政策和评价人口政策改变所带来的影响将有重要的意义。

Social network is the core of social capital and has important impacts on individual economic behavior. This project will examine the influence of social network through a new angle, i.e., the impact of population policy on individual economics behavior. On the macro side, rapid population growth increases population density and intensifies the relationship among individual. On the micro side, population policy affects family birth rate, which determines the size of family and relatives. Thus, the size and structure of individual’s social network are affected by population policy. This project will investigate the impact of population policy through social network on entrepreneurship, saving and household asset investment. We will start from the theoretical analysis and the discussion of three major mechanisms: risk-sharing, relaxation of credit constraint and the transmission of information. We will propose the main hypotheses and test them with multiple national-wide household-level survey data and our own survey data about complete social network in representative villages. Our research will have great implications for the current population policy design and the evaluation of its consequences.