[bzbarsky]

The "expensive preparatory courses" offer something like a 10-30 point benefit over checking out an SAT prep book from the library, if you control for the time spent on preparation, last I checked.

What the courses do offer, of course, is the structure to force indifferent students to sit through the preparation.

There's a lot of bad statistics, whether by accident or with an agenda, being done around the SAT....

But more important than all that, as the MIT post says, pretty much all the other measures elite colleges use for admitting students correlate even _more_ with income than the SAT does.