As for the federal government, no one yet knows how it will perform its evaluation. Arne Duncan, the education secretary, has said that his goal is a ratings system, not a single first-place-to-last-place ranking, and that the ratings will compare only schools that are similar in their mission, their student population and so on. Harvard and Yale, that is; not Harvard and Soka University of America.

“We’ll be looking at access,” Mr. Duncan said in a recent speech, “such as the percentage of students receiving Pell grants. We’ll be looking at affordability, like average tuition, scholarships and loan debt. And we’ll be looking at outcomes, such as graduation and transfer rates, alumni satisfaction surveys, graduate earnings and the advanced degrees of college graduates.”

In search of the best way to measure those categories, and of other kinds of information that ought to be included, Education Department officials will soon fan out across the country for months of town hall meetings, school forums and interviews. The plan is to compile the ratings by the start of the 2015-16 school year and to link those ratings to federal aid by 2018.

But Carolyn Hoxby, a Stanford professor and an author of an influential study about the failures of college as an engine for social mobility, said the effort is doomed to fail.

“I do not believe the federal government currently has the capacity to generate a ratings system that will even be neutral,” she said. “I think it’s more likely that it will be harmful to students.”

A truly useful analysis, she suggested, would have two main parts. “One, a lot of information about the outcomes for students — sometimes obvious things, like earning and employment, but also whether they serve in the public sector, whether they give back to society, do people have stable families, how do their kids turn out, do they end up dependent on social programs.”

The second requirement, she said, would be the ability to control for variations in the student body. “Let’s say you looked at Harvard, Yale, Stanford,” she explained. “You’d say they have all these great outcomes. But that doesn’t necessarily mean that’s the value added by those colleges, because their students were terrific” to begin with.