For example, full tuition and fees at Princeton this year is more than $50,000, while Rutgers, the state university just up the New Jersey Turnpike, costs state residents less than half that. The figures are similar for the University of Pennsylvania and Pennsylvania State University. (For the sake of this exercise, set aside those students at elite colleges whose financial aid packages cover most, if not all, of their education.)

Despite the lingering gap in pricing between public and private schools, Eric R. Eide, one of the authors of that paper on the earnings of blue-chip college graduates, said he had seen no evidence that would persuade him to revise, in 2010, the conclusion he reached in 1998.

“Education is a long-run investment,” said Professor Eide, chairman of the economics department at Brigham Young, “It may be more painful to finance right now. People may be more hesitant to go into debt because of the recession. In my opinion, they should be looking over the long run of their child’s life.”

He added, “I don’t think the costs of college are going up faster than the returns on graduating from an elite private college.”

Still, one flaw in such research has always been that it can be hard to disentangle the impact of the institution from the inherent abilities and personal qualities of the individual graduate. In other words, if someone had been accepted at an elite college, but chose to go to a more pedestrian one, would his earnings over the long term be the same?

In 1999, economists from Princeton and the Andrew W. Mellon Foundation looked at some of the same data Professor Eide and his colleagues had used, but crunched them in a different way: they compared students at more selective colleges to others of “seemingly comparable ability,” based on their SAT scores and class rank, who had attended less selective schools, either by choice or because a top college rejected them.