Monday, April 20, 2009

Predicting Performance

Malcolm Gladwell had an interesting article from a few months back that is about predicting performance of quarterbacks, and teachers. Essentially the take home message was that in a great many professions you simply can't predict in advance who will be good at the job. That leads to interesting predictions about how we should bring people into the field.

"Eric Hanushek, an economist at Stanford, estimates that the students of a very bad teacher will learn, on average, half a year's worth of material in one school year. The students in the class of a very good teacher will learn a year and a half's worth of material. That difference amounts to a year's worth of learning in a single year. Teacher effects dwarf school effects: your child is actually better off in a "bad" school with an excellent teacher than in an excellent school with a bad teacher. Teacher effects are also much stronger than class-size effects. You'd have to cut the average class almost in half to get the same boost that you'd get if you switched from an average teacher to a teacher in the eighty-fifth percentile. And remember that a good teacher costs as much as an average one, whereas halving class size would require that you build twice as many classrooms and hire twice as many teachers."

"Douglas Staiger, an economist at Dartmouth; and Robert Gordon, a policy analyst at the Center for American Progress—have investigated whether it helps to have a teacher who has earned a teaching certification or a master's degree. Both are expensive, time-consuming credentials that almost every district expects teachers to acquire; neither makes a difference in the classroom. Test scores, graduate degrees, and certifications—as much as they appear related to teaching prowess—turn out to be about as useful in predicting success as having a quarterback throw footballs into a bunch of garbage cans."

"In teaching, the implications are even more profound. They suggest that we shouldn't be raising standards. We should be lowering them, because there is no point in raising standards if standards don't track with what we care about. Teaching should be open to anyone with a pulse and a college degree—and teachers should be judged after they have started their jobs, not before."

"Similarly, all quarterbacks drafted into the pros are required to take an I.Q. test—the Wonderlic Personnel Test. The theory behind the test is that the pro game is so much more cognitively demanding than the college game that high intelligence should be a good predictor of success. But when the economists David Berri and Rob Simmons analyzed the scores—which are routinely leaked to the press—they found that Wonderlic scores are all but useless as predictors. Of the five quarterbacks taken in round one of the 1999 draft, Donovan McNabb, the only one of the five with a shot at the Hall of Fame, had the lowest Wonderlic score. And who else had I.Q. scores in the same range as McNabb? Dan Marino and Terry Bradshaw, two of the greatest quarterbacks ever to play the game."

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