That said, I did read the entire paper before posting the first time — including pages 12-16. Please point out anything that I’ve said that’s factually incorrect. If I made a mistake, I’ll be happy to admit it and correct it. Otherwise, please refrain from belittling me or my intelligence.

The study is rigorous, but it is not the final word on the topic. Besides the issues with the sample that I already discussed you can also throw in the facts that:

1.) It was only in North Carolina

2.) There was no foolproof way to decide which students had which teachers. Ultimately they decided that they were pretty sure about which teachers 84% of the kids had, and eliminated the rest.

3. There was no longitudinal data for the tests. Students didn’t take tests in the same subjects more than once, so they had to compare their performance on each test to their performance on tests in other subjects that year rather than tests in the same subjects the previous year (e.g. gain scores).

The authors went pretty far out of their way to address all of these issues, so it’s certainly possible that the results would hold up if perfect information was available. But the fact is that perfect information is not available and I have a problem with anybody who argues that this study definitively proves anything. It provides compelling evidence in one direction but, like any study, has flaws and I don’t accept something as the truth just b/c the authors conducted sophisticated quantitative analyses.

I’m not going to argue that that specification overestimated the effects of TFA teachers, b/c I have no idea what the outcome would be if they used equal comparison groups.

Lastly, in some ways the study probably underestimates the effects of TFA teachers by assuming that the other teachers in the state would be the ones teaching the kids were TFA not in place. It’s more likely that the spots filled by TFA teachers would instead be filled by teachers significantly less qualified and experienced than the average NC teacher.

“Which I think is the nicest thing one can say about a study.”

Among economists the nicest thing you can say is that it’s worth attacking. That’s how they roll.

Corey, what are they teaching you at Vanderbilt?

The study compared TFA teachers in NC to non-TFA teachers in the same schools. If the TFAers weren’t there, the kids would have had the other teachers, and learned less.

Of course, it’s equally possible that they are even better than estimated as it is that they’re worse.

It’s a bit saddening, too, though; what does it say about the existing teachers in those schools that inexperienced twenty-two-year-olds who frequently have no management skills whatsoever — in other words, who probably aren’t doing all that good a job, on average — still outperform them?