班级规模、同伴特征与初中生学业能力——来自中国经验数据的证据

Class Size,Peer Characteristics and Junior Middle School Students'Academic Ability:Evidence from Empirical Data in China

缩小班级规模是国内外广泛关注的一种提高教学质量并促进教育公平的方式。本文基于中国教育追踪调查(CEPS)数据,采用多层次模型研究班级规模对初中生学业能力的影响。在优质教育资源匮乏的情况下,不同类型的班级生源质量存在明显的差异,大班往往拥有更好的生源,这是导致出现班级规模正向效应估计偏差的主要原因。本研究尝试讨论不同类型班级的班级规模影响学业能力的机制。研究发现,班级规模与学业能力之间存在“倒U型”的非线性关系。中介效应分析结果表明不同类型班级的班级规模影响学业能力的机制不同,其中非大班的班级规模产生正向效应的主要作用路径是同伴效应,但是当班级规模增加到一定程度后,拥挤效应成为班级规模负向效应的主要作用机制。另外,班级规模对不同类型学生的影响存在异质性,适度增加班级人数对所有分位点的学生均产生显著的正向影响,且影响程度基本无差异。然而,当班级规模极度扩张时,学业能力较强的学生对拥挤带来的负向效应更敏感。

Reducing class size is an educational investment method that is widely concerned to improve quality and promote education equity.Based on the data of China Education Panel Survey(CEPS),we use Hierarchical Linear Model to study the effects of class size on junior middle school students'academic ability.In the absence of high-quality education resources,there are obvious differences in the quality of students in different types of classes.Large classes often have better students,which is the main reason for the estimation bias of the positive effect of class size.We found that there is an approximately inverted-U relationship between class size and academic ability.Mediation effect test shows that there are differences in the impact mechanism of class size effect in different type of classes,performance may increase as class size rises initially because of peer effects,and fall when congestion effects start to dominate.In addition,research shows that the influence of class size on different types of students is heterogeneous,moderate increase in class size has a significant positive impact on all quantile students,and the degree of the impact is similar.However,when the class size is extremely expanded,students with strong academic ability are more sensitive to congestion effects.