At public colleges, then, the explanation for rising tuition prices isn’t spiraling costs. The costs are the same, but the burden of paying those costs has shifted from state taxpayers to students.

Given this structure, can a ratings system affect tuition prices at public colleges? Not really.

Economic theory predicts that in a competitive market, informed consumers will choose the cheapest option that meets their needs. This puts competitive pressure on businesses to hold prices down.

But consumers cannot do much when they learn that their state’s colleges are expensive. For example, public four-year colleges are much more expensive in Illinois (averaging about $12,000 a year for state residents) than in Wyoming ($4,400). But the two states don’t compete with each other for students at these prices, which are restricted to residents. In fact, Wyoming charges $14,000 for out-of-state students, which makes it cheaper for the Illinois resident to stay home.

Of course, Illinois residents could vote with their feet by moving to Wyoming. But mass migration was probably not the mechanism the Obama administration had in mind for reducing college costs.

The bottom line is that better-informed consumers can’t do much to hold down prices in public colleges, because those prices are not set in a competitive market. Instead, they are determined through a political process, so it is only through the ballot box that people can affect them. Perhaps one of the quiet goals of the proposed rating system is to rally voter support for increased funding for public colleges.

When it comes to private colleges, I am more optimistic that the rating system could affect consumer choices and college prices.

Many private, four-year colleges compete nationally for students. A transparent rating could help a student who is wavering among several such schools to pick the least expensive one. And many private colleges have close substitutes in the public sector, where tuition prices are much lower. In particular, community colleges and two-year, for-profit colleges (known as proprietary schools) offer many of the same training programs — but the proprietary schools almost always charge much higher tuition, and their students take on larger loans. A rating system could nudge these students toward the cheaper community colleges.