From Who Needs Harvard? by Gregg Easterbrook:
...what if ... the idea that getting into an elite college makes a big difference in life—is wrong? What if it turns out that going to the "highest ranked" school hardly matters at all?
The researchers Alan Krueger and Stacy Berg Dale began investigating this question, and in 1999 produced a study that dropped a bomb on the notion of elite-college attendance as essential to success later in life. Krueger, a Princeton economist, and Dale, affiliated with the Andrew Mellon Foundation, began by comparing students who entered Ivy League and similar schools in 1976 with students who entered less prestigious colleges the same year. They found, for instance, that by 1995 Yale graduates were earning 30 percent more than Tulane graduates, which seemed to support the assumption that attending an elite college smoothes one's path in life.
But maybe the kids who got into Yale were simply more talented or hardworking than those who got into Tulane. To adjust for this, Krueger and Dale studied what happened to students who were accepted at an Ivy or a similar institution, but chose instead to attend a less sexy, "moderately selective" school. It turned out that such students had, on average, the same income twenty years later as graduates of the elite colleges. Krueger and Dale found that for students bright enough to win admission to a top school, later income "varied little, no matter which type of college they attended." In other words, the student, not the school, was responsible for the success.