Estimating Class‐size Effects using Within‐school Variation in Subject‐specific Classes
提出一种利用校内不同学科班级规模随时间变化的新识别策略，以解决家长择校带来的选择偏差问题，并应用于丹麦数据发现缩小班级规模对法语成绩有显著正向影响，对学业薄弱学生和男生效果更大。
Selection response of parents to low school quality, for instance large class sizes, is a major problem when estimating causal class-size effects, also in experimental and quasi-experimental studies. To address this problem a new identification strategy using within-school variation over time in the size of subject-specific classes is proposed. It provides random class-size variation and enables tests for possible selection using test scores in other subjects. Applying this approach to Danish administrative data, highly significant and substantial positive effects of reducing class size are found on examination marks in French. Effects are larger for academically weak students and for boys. Copyright © The Author(s). Journal compilation © Royal Economic Society 2009.