空间距离和朋友网络的同群效应:来自小学随机实验的证据

Peer Effects through Spatial Distance and Friend Networks:Evidence from a Randomized Experiment in Elementary Schools

基础教育阶段学生行为的可塑性很强,容易受到周围人群的影响,同伴可能影响他们短期甚至整个生命周期的表现,理解同伴对学生行为和成绩的影响具有现实意义。本文在中国某县10所小学的72个班级进行随机实验,通过在班级内随机安排学生的座位,外生改变学生间的座位距离,进而改变他们的朋友网络关系,从而识别空间距离和朋友网络两个维度的同群效应,并重点关注后者。研究发现,处于高成绩朋友的网络中可以使得个体学习成绩提高0.05个标准差,朋友网络可以解释空间距离同群效应的65%。在对朋友网络的影响机制分析中,本文发现个体的学习时间、阅读时间和参加辅导的概率均会受到他们朋友相同行为的影响。

Student behaviour,especially in the basic education stages,is highly malleable.Children may be affected by their peers,determining their short-and long-term performance.Therefore,it is of practical importance to understand the effects of peers on child behaviour and academic performance.This paper conducts a randomised experiment in 72 classes among 10 elementary schools in a county in China,in order to disentangle the network peer effects from the spatial distance peer effects.At the start of the semester,student seats are randomly allocated in each class,and it is observed that different distances between them incur an exogenous variation in the student friendship structure.The study shows that being placed in a good network containing friends with higher academic performance can improve student scores by 0.05 standard deviations and controlling friend networks reduces the spatial distance peer effects by 65%.When analysing the mechanisms of network peer effects,we find that the individual's study time,reading time and the likelihood of participating in tutoring are positively affected by the same behaviour in their friends.