The ruling by America’s Supreme Court in June that in effect banned universities from using racial preferences in admissions sparked two lively debates. Although the better publicised argument was over whether the decision represented an advance or a setback for equality of opportunity, perhaps the more interesting one focused on whether the admissions decisions of a handful of selective institutions deserved so much attention to begin with. Just 6% of American undergraduates attend colleges that accept less than a quarter of their applicants, leaving the vast majority unaffected. Moreover, most academic analyses of the socioeconomic impact of a bachelor’s degree from highly selective colleges have failed to quantify just what it is that they add. Although these universities’ alumni do have unusually high incomes after leaving college, they also had unusually strong high-school qualifications before they went. One study, by Stacy Dale and Alan Krueger of Princeton, found that those who attend higher-ranked universities do not, on average, wind up earning more money than do those who go to lower-ranked ones. This suggests that the …