If you've applied to college recently, you've probably bitched about the SATs and noted that, frankly, they suck. You may have wondered why--after all your years of labor, AP courses, extra-curriculars, and the like--you are going to be judged in part or in whole on one number, one single number, that you earned in a few nasty, brutish, and short hours.

I thought I'd try to explain.

It's actually depressingly simple. Suppose you're the head of the admissions office. Your job is to select exceptional students, or, at the very least, to select candidates who won't burn out and fail out in a year or two. You've received, say, 15,000 applications for 1500 spots. There's no way you can read, judge, and rank 15,000 applications in the time you have available. You have to winnow it down to a smaller number of applications--to a number that you can actually read and evaluate.

The SAT is specifically marketed for this purpose. It's a test that's designed to predict success in college. It turns out that if you pick an applicant from the High-SAT group of students, you can be relatively sure that you've got a successful student. If you pick from the Low-SAT group of students, you can't be as sure. Now, remember your goal: you're trying to reduce your application pool to a smaller, more manageable size, and ideally you'll have as many successful students as possible in that pool. From which SAT group will you pick?

Yep. If you want to achieve your goal, you have to pick from the High-SAT pool. Then you can look at those people more closely to see if you can get rid of the other folks from the High-SAT pool who won't make it. (In practice, of course, you'd also probably look at the GPA or the AP scores of the Low-SAT batch to try to pick up one or two particularly good kids.)

That's it. That's all. It doesn't matter that the test covers juvenile math and uses boring reading-comprehension questions. It doesn't matter that the test doesn't give you any ability to express your true intelligence (whatever that is). It doesn't matter if nobody can figure out why it predicts success; it only matters that it does so predict, and, according to the evil monopolists at ETS, it does. Sure, it's nice that all (or most) students receive exactly the same test, but its predictive ability is most important. Heck, colleges would judge you on your nose size if that were a better predictor.

Sorry. Keep reading those Princeton Review books.