Democratization or Diversion? The Effect of Community Colleges on Educational Attainment
利用社区大学入学机会的差异作为工具变量，分析社区大学对教育成就的影响，发现社区大学虽能增加总受教育年限，但会分流部分原本可能上四年制大学的学生，降低其完成学士学位的可能性。
This article estimates the impact of community colleges on educational attainment. Community colleges give those who might not have otherwise attended college the ability to do so (democratization); they also attract students who might otherwise have attended a four-year college (diversion). The effect of democratization on educational attainment is nonnegative; the effect of diversion is unclear a priori. I use variation in access to community colleges as instrumental variables to address self-selection into types of colleges. The results suggest that two-year college students diverted from a four-year college complete fewer years of education. Overall, however, community colleges appear to increase total years of schooling but do not appear to change the likelihood of attaining a bachelor's degree.