From a new NBER working paper by Eric Hanushek comes this shocking abstract:

A teacher one standard deviation above the mean effectiveness annually generates marginal gains of over $400,000 in present value of student future earnings with a class size of 20 and proportionately higher with larger class sizes. Alternatively, replacing the bottom 5-8 percent of teachers with average teachers could move the U.S. near the top of international math and science rankings with a present value of $100 trillion.

There are really two important claims here. I think progressives tend to be very pleased with claims like the first one, which is that teachers have a very high value. You can find similar results in the work of Raj Chetty, which suggests that good kindergarten teachers are worth $320,000. If this is true then the marginal benefit of teaching skill -or quality, if you want to think of it that way- is far below the marginal cost, and therefore we should increase wages to draw more talented teachers.

However, the second claim is just as important and is suggested by, although not a necessary condition of, the first: if good teachers are very valuable, then bad teachers are very costly. This means we should be willing to pay more for good teachers, but it also increases the benefit of getting rid of bad teachers and ensuring we have a system that can do that.  After all, every dollar spent on a bad teacher has the high opportunity cost of good teachers.

Findings like this tell us that we should place even less relative value on teacher well-being for it’s own sake (which is separate from teacher well-being to the extent that it improves outcomes) when considering reforms. I think this is something that some progressives aren’t as happy to hear, especially with regard to using the teaching profession as a middle class jobs program.

Overall though these results reinforce one fact that progressives and conservatives should agree on: this is a really important issue.

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