Socio-economic diversity is the latest wrinkle in the ongoing diversity mania. It’s based on the notion that schools are doing something to combat economic inequality by admitting students from poor families who don’t really have great academic abilities, but will still be able to get through the likes of Harvard, Duke, or similar institutions.

Back in 1999, Alan Krueger and Stacy Dale wrote a paper published by the National Bureau of Economic Research (not available online) entitled “Estimating the Payoff to Attending a More Selective College.” They found, after examining a dataset consisting of students who had been admitted to an elite school but chose to attend a less prestigious one instead, that it really didn’t matter whether the student went to the elite school or the less prestigious one. The elite institutions may think that they provide a significantly better education than those further down the US News rankings, but there is little reason to believe that.

We should also keep in mind that in the still mostly meritocratic U.S. economy, how well one does has very little to do with educational credentials. People progress (or not) based on their productivity. Someone who graduated from an unheard-of school (or none at all) may succeed far more than someone who graduated from an Ivy but lacks drive and determination. Elite school credentials may help you get your first job, but after that you’re on your own.

Ah, but there is a downside. Students who don’t have the academic abilities of those who are admitted without any preferences may find that they struggle in the tough competition of the elite institution and graduate with a rather low class ranking. Arguably, a high class ranking at a second-tier school is better for one’s prospects than a low class ranking at a prestige school. All of this is ably discussed in a 2004 paper by Princeton’s Russ Nieli entitled “The Changing Shape of the River.”

Another problem that the advocates of admissions preferences don’t want to discuss is the fact that when schools admit students on the basis of various characteristics who wouldn’t make the cut just on academic ability, they create problems for the professors. It’s difficult to adjust one’s course if there is a substantial intellectual gap between students. Since there is pressure these days to make sure that the affirmative-action students don’t do poorly, the result is a watering down of courses and grade inflation.