Income Segregation and Intergenerational Mobility Across Colleges in the United States*
Quarterly Journal of Economics · 2020 · Raj Chetty、John N. Friedman、Emmanuel Saez、Nicholas Turner、Danny Yagan
中文摘要
我们利用税务记录中的去标识化数据，为美国每所高校构建了关于父母收入和学生收入结果的公开统计数据。这些统计数据表明，高校之间父母收入隔离的程度非常高，与社区之间的收入隔离程度相近。在就读于同一所高校的学生中，来自低收入家庭与高收入家庭的子女在大学毕业后收入方面的差异，远小于不同高校之间的差异。收入结果最好的高校主要招收高收入家庭的学生，不过也有少数中等层次的公立高校兼具较低的父母收入水平和较高的学生收入。我们将这些收入数据与SAT和ACT成绩相匹配，以模拟学生在高校之间的分配发生变化会如何影响收入隔离和代际流动。在给定考试成绩的条件下，若使各父母收入群体的申请率、录取率和入学率趋于一致，收入隔离程度将大幅下降，这主要是因为中产阶级学生在选择性更强的高校中的占比会提高。然而，这种调整对精英私立高校中低收入学生的比例影响不大，因为来自低收入家庭且SAT或ACT成绩足够高的学生相对较少。如果在申请和录取过程中给予低收入和中等收入学生按收入水平浮动的优惠待遇，其程度类似于精英私立高校隐性给予校友子女的优惠待遇，就可以消除高校之间父母收入分布的差异。假设在给定考试成绩、种族和父母收入的条件下，观测到的学生收入差异中有80%源于高校的因果效应——这是一个很强的假设，但与既有研究一致——那么上述调整可使高校学生的代际收入持续性降低约25%。我们的结论是，即使不改变高校的教育项目，改变学生在高校之间的分配方式也能大幅减少收入隔离并提高代际流动。
Abstract
Abstract We construct publicly available statistics on parents’ incomes and students’ earnings outcomes for each college in the United States using deidentified data from tax records. These statistics reveal that the degree of parental income segregation across colleges is very high, similar to that across neighborhoods. Differences in postcollege earnings between children from low- and high-income families are much smaller among students who attend the same college than across colleges. Colleges with the best earnings outcomes predominantly enroll students from high-income families, although a few mid-tier public colleges have both low parent income levels and high student earnings. Linking these income data to SAT and ACT scores, we simulate how changes in the allocation of students to colleges affect segregation and intergenerational mobility. Equalizing application, admission, and matriculation rates across parental income groups conditional on test scores would reduce segregation substantially, primarily by increasing the representation of middle-class students at more selective colleges. However, it would have little effect on the fraction of low-income students at elite private colleges because there are relatively few students from low-income families with sufficiently high SAT/ACT scores. Differences in parental income distributions across colleges could be eliminated by giving low- and middle-income students a sliding-scale preference in the application and admissions process similar to that implicitly given to legacy students at elite private colleges. Assuming that 80% of observational differences in students’ earnings conditional on test scores, race, and parental income are due to colleges’ causal effects—a strong assumption, but one consistent with prior work—such changes could reduce intergenerational income persistence among college students by about 25%. We conclude that changing how students are allocated to colleges could substantially reduce segregation and increase intergenerational mobility, even without changing colleges’ educational programs.