Many low-income high achievers never think of applying to selective schools.
In The Missing "One-Offs": The Hidden Supply of High-Achieving, Low Income Students (NBER Working Paper No. 18586), Caroline Hoxby and Christopher Avery study every student in the high school graduating class of 2008 who scored at the 90th percentile or above on the SAT or ACT and whose high school GPA was A- or above. They show that despite the fact that these high-achievers are well qualified for admission at America's most selective colleges, the vast majority of low-income high achievers do not apply to any selective school.
More than 50 percent of low-income high achievers apply exclusively to non-selective two-year and four-year schools that typically have low graduation rates and low instructional resources. Only 8 percent of them apply in a manner similar to that of high-income high achievers, who normally apply to several "peer" schools where the median student has scores like their own, the graduation rate is high, and instructional resources are ten times those at non-selective schools. High-income high achievers also usually apply to a few "reach" and "safety" schools.
These authors show that because low-income high achievers rarely apply to selective colleges, there are many more low-income high achievers than admissions staff thought. What the admissions staff see are eight to fifteen high-income applicants for every low-income applicant. However, the ratio of high-income high achievers to low-income high achievers is only about two-to-one in the population.
The authors eliminate a number of explanations for low-income high achievers' failure to apply to selective colleges, including cost. They show that very selective colleges offer high-achieving, low-income students such generous financial aid that they could attend these colleges and pay less than they are currently paying to attend the much less selective colleges in which they enroll.
Nor do low-income high achievers fail if they apply to selective colleges. The authors show that if a low-income student and a high-income student with the same achievement apply to the same college, they have outcomes (matriculation, persistence, on-time graduation) that are so similar that they cannot be distinguished statistically.
A lack of effort on the part of selective colleges does not explain these results, either. Their admissions staffs visit hundreds of high schools, organize campus visits, and work with many local college mentoring programs.
Why, then, do the vast majority of low-income, high-achievers not apply to very selective colleges? The authors show that those who do not apply are dispersed: they are "one-offs" in their high schools and localities. Thus, there is no cost-effective way for colleges to reach them using the traditional methods listed above, all of which work best when students attend a school with a critical mass of high achievers (such as a magnet school) or live near a selective college (such as the Harlem students who live near Columbia University). This dispersion also explains why the students' counselors do not develop expertise about very selective colleges. If a counselor has 350 advisees (the typical number in the United States) and only encounters a high achiever once every few years, that counselor will develop skills to help her other advisees -- many of whom may be struggling to stay in school or attend any postsecondary institution -- rather than skills that will help the rare one-off.