This paper uses a quasi-natural policy experiment in Germany, the G8 reform, to examine the impact of schooling intensity on student learning. The G8 reform compresses secondary school for academic-track students from nine to eight years, while holding fixed the overall academic content and total instruction time required for graduation, resulting in a higher schooling intensity per grade. Using German extension of the Programme for International Student Assessment data, we find that this reform improves test scores on average, but the effect differs across subgroups of students. The reform effect is larger for girls than for boys, for students with German-born parents than for those with immigrant parents, and for students having more books at home. The heterogeneous reform effects cannot be explained by changes in observed channels. Instead, quantile regression results suggest that unobserved heterogeneity plays an important role: Whereas high-performing students significantly improve their test scores, the lowest-performing students hardly improve at all after the reform. We interpret the unobserved heterogeneity as reflecting students’ capability to cope with the increase in schooling intensity.

中文翻译：

---

上学强度对学生学习的影响：一项准实验的证据

本文使用德国在八国集团（G8）进行的准自然政策实验来检验就学强度对学生学习的影响。八国集团（G8）的改革将学术领域的中学的压缩时间从九年压缩为八年，同时保持了固定的整体学术内容和毕业所需的总教学时间，从而提高了每个年级的教育强度。使用国际学生评估计划数据的德语扩展，我们发现这种改革平均可以提高考试成绩，但是不同学生群体的效果有所不同。对于男孩来说，女孩的改革效果要比男孩大；对于有德国出生父母的学生，比有移民父母的学生，以及在家拥有更多书的学生，改革效果更大。不能通过观察渠道的变化来解释异质改革的效果。代替，分位数回归结果表明，未观察到的异质性起着重要作用：虽然成绩优异的学生显着提高了他们的考试成绩，但成绩最低的学生在改革后几乎根本没有提高。我们将未观察到的异质性解释为反映学生应对上学强度增加的能力。