Estimating the Cream Skimming Effect of School Choice
推导出一个公式来衡量学校选择项目通过吸引优秀学生离开而对留在公立学校的学生造成的伤害程度，并用该公式评估假设的学券计划对公立学校留校生高中毕业率等结果的影响，发现影响很小。
We derive a formula to determine the degree to which a school choice program may harm public school stayers by luring the best students to other schools. The "cream skimming" effect is increasing in the degree of heterogeneity within schools, the school choice take-up rate of strong students relative to weak students, and the dependence of school outcomes on student body quality. We use the formula to investigate the cream skimming effect of hypothetical voucher programs on the high school graduation rate and other outcomes of the students who would remain in public school. We find small effects across a wide variety of model specifications and types of modest voucher programs.