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New Study Indicates That Teacher Bonuses Don’t Improve Student Test Scores

Linda Pearlstein summarizes a pretty good new controlled study from Vanderbilt University that tested the idea that offering teachers bonuses of up to $15,000 could improve student outcomes. The results — nope:

With one exception researchers could not fully explain — fifth grade — they found that students of teachers eligible for bonuses performed no better than other students. The teachers in one group did not approach instruction differently from those in the other, and where they did, it did not affect student achievement. Scores went up for both groups, “a trend that is probably due to some combination of increasing familiarity with a criterion-referenced test introduced in 2004 and to an intense, high-profile effort to improve test scores to avoid NCLB sanctions.”

I’m not surprised that this didn’t work, but it is worth dwelling on the fact that it’s too bad that it doesn’t seem to work. As Pearlstein writes “presuming that merit pay alone would elevate student achievement makes sense if you assume teachers have a hidden trove of skills and effort they are not unloosing on their students only because they lack the proper incentives to do so.” I don’t think that was ever a very psychologically plausible account of what’s happening in American classrooms. But imagine if it was correct. Say we had a legion of roughly average teachers who knew perfectly well how to turn themselves into excellent teachers if it was only worth their while. Well then we’d be on easy street. Offer bonuses, teachers will try harder, kids will learn more, teachers will earn more, and the more productive economy down the road will easily pay for the bonuses. It’d be a win-win-win universe.

It sounds implausible, however, and it doesn’t appear to be accurate (though it’s not like anyone suffered in this experiment — kids learned more across the board).

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This is one reason why I’ve never really liked the term “merit pay” or the rhetoric around it. The right way to think about teacher compensation, I think, is this. You could have a system in which all teachers are paid the same amount. But we don’t have that system. Instead we have a system where veteran teachers are paid much more than novice teachers, and teachers with master’s degrees are paid more than teachers without master’s degrees. We could switch this to a system where teachers whose kids do much worse than average on value-added measures get fired, and teachers whose kids to much better than average get paid more than average teachers. The idea here wouldn’t so much be to create an “incentive” as simply to ensure that the best teachers aren’t tempted to leave the profession while the worst teachers are encouraged to do so. If you want to do something through a bonus/incentive mechanism, what would make sense is to offer teachers extra money to take on challenging assignments in high poverty schools.

The point is that an absolutely flat salary structure makes no sense. Instead, we prefer to rely on proxies for quality. Currently, we use length of service and possession of a master’s degree as our proxies. But the evidence suggests that these are bad proxies and that value-added metrics, despite their flaws, are better.