The Long-Term Impacts of Low-Achieving Childhood Peers: Evidence from Project STAR
利用STAR项目随机分配数据，发现与低成就留级生同班虽短期降低数学成绩，但长期提升非认知技能（如努力和纪律），并增加高中毕业和参加大学入学考试的概率。
Abstract This paper evaluates how sharing a kindergarten classroom with low-achieving repeaters affects the long-term educational performance of regular first-time kindergarten students. Exploiting random assignment of teachers and students to classes in Project STAR, I document three sets of causal impacts: students who are exposed to repeaters (1) score lower on a standardized math test at the end of kindergarten, an effect that fades out in later grades; (2) show persistent improvements in noncognitive skills such as effort and discipline; and (3) are more likely to graduate from high school and to take a college entrance exam around the age of 18. I argue that the positive spillovers on long-term educational attainment are driven by the differential accumulation of noncognitive skills by repeater-exposed students during childhood. Results are consistent with the hypothesis that the improvements in these skills are driven by behavioral adjustments of teachers to the presence of repeaters in the classroom.