third, or intensive margin,' combines the increasing self-segregation (on the basis of aptitude) of students among colleges …

reductions in class size from a base of 15 to 30 students have no effect on student achievement. The estimates are precise enough … the presence of black students in a class, in an of itself, has no effect on achievement. I demonstrate that estimates of …

students respond to their menus' like rational human capital investors. Whether they make the investments efficiently is … aptitude students respond to aid in a way that apparently reduces their lifetime present value. While both a lack of … sophistication/information and credit constraints can explain the behavior of this 30 percent of students, the weight of the evidence …