VAMboozled!: Using VAMs “In Not Very Intelligent Ways:” A Q&A with Jesse Rothstein
The American Prospect — a self-described “liberal intelligence” magazine — featured last week a question and answer, interview-based article with Jesse Rothstein — Professor of Economics at University of California – Berkeley — on “The Economic Consequences of Denying Teachers Tenure.” Rothstein is a great choice for this one in that indeed he is an economist, but one of a few, really, who is deep into the research literature and who, accordingly, has a balanced set of research-based beliefs about value-added models (VAMs), their current uses in America’s public schools, and what they can and cannot do (theoretically) to support school reform. He’s probably most famous for a study he conducted in 2009 about how the non-random, purposeful sorting of students into classrooms indeed biases (or distorts) value-added estimations, pretty much despite the sophistication of the statistical controls meant to block (or control for) such bias (or distorting effects). You can find this study referenced here, and a follow-up to this study here.
In this article, though, the interviewer — Rachel Cohen — interviews Jesse primarily about how in California a higher court recently reversed the Vergara v. California decision that would have weakened teacher employment protections throughout the state (see also here). “In 2014, in Vergara v. California, a Los Angeles County Superior Court judge ruled that a variety of teacher job protections worked together to violate students’ constitutional right to an equal education. This past spring, in a 3–0 decision, the California Court of Appeals threw this ruling out.”
Here are the highlights in my opinion, by question and answer, although there is much more information in the full article here:
Cohen: “Your research suggests that even if we got rid of teacher tenure, principals still wouldn’t fire many teachers. Why?”
Rothstein: “It’s basically because in most cases, there’s just not actually a long list of [qualified] people lining up to take the jobs; there’s a shortage of qualified teachers to hire.” In addition, “Lots of schools recognize it makes more sense to keep the teacher employed, and incentivize them with tenure…”I’ve studied this, and it’s basically economics 101. There is evidence that you get more people interested in teaching when the job is better, and there is evidence that firing teachers reduces the attractiveness of the job.”
Cohen: Your research suggests that even if we got rid of teacher tenure, principals still wouldn’t fire many teachers. Why?
Rothstein: It’s basically because in most cases, there’s just not actually a long list of people lining up to take the jobs; there’s a shortage of qualified teachers to hire. If you deny tenure to someone, that creates a new job opening. But if you’re not confident you’ll be able to fill it with someone else, that doesn’t make you any better off. Lots of schools recognize it makes more sense to keep the teacher employed, and incentivize them with tenure.
Cohen: “Aren’t most teachers pretty bad their first year? Are we denying them a fair shot if we make tenure decisions so soon?”
Rothstein: “Even if they’re struggling, you can usually tell if things will turn out to be okay. There is quite a bit of evidence for someone to look at.”
Cohen: “Value-added models (VAM) played a significant role in the Vergara trial. You’ve done a lot of research on these tools. Can you explain what they are?”
Rothstein: “[The] value-added model is a statistical tool that tries to use student test scores to come up with estimates of teacher effectiveness. The idea is that if we define teacher effectiveness as the impact that teachers have on student test scores, then we can use statistics to try to then tell us which teachers are good and bad. VAM played an odd role in the trial. The plaintiffs were arguing that now, with VAM, we have these new reliable measures of teacher effectiveness, so we should use them much more aggressively, and we should throw out the job statutes. It was a little weird that the judge took it all at face value in his decision.”
Cohen: “When did VAM become popular?”
Rothstein: “I would say it became a big deal late in the [George W.] Bush administration. That’s partly because we had new databases that we hadn’t had previously, so it was possible to estimate on a large scale. It was also partly because computers had gotten better. And then VAM got a huge push from the Obama administration.”
Cohen: “So you’re skeptical of VAM.”
Rothstein: “I think the metrics are not as good as the plaintiffs made them out to be. There are bias issues, among others.”
Cohen: “During the Vergara trials you testified against some of Harvard economist Raj Chetty’s VAM research, and the two of you have been going back and forth ever since. Can you describe what you two are arguing about?”
Rothstein: “Raj’s testimony at the trial was very focused on his work regarding teacher VAM. After the trial, I really dug in to understand his work, and I probed into some of his assumptions, and found that they didn’t really hold up. So while he was arguing that VAM showed unbiased results, and VAM results tell you a lot about a teacher’s long-term outcomes, I concluded that what his approach really showed was that value-added scores are moderately biased, and that they don’t really tell us one way or another about a teacher’s long-term outcomes” (see more about this debate here).
Cohen: “Could VAM be improved?”
Rothstein: “It may be that there is a way to use VAM to make a better system than we have now, but we haven’t yet figured out how to do that. Our first attempts have been trying to use them in not very intelligent ways.”
Cohen: “It’s been two years since the Vergara trial. Do you think anything’s changed?”
Rothstein: “I guess in general there’s been a little bit of a political walk-back from the push for VAM. And this retreat is not necessarily tied to the research evidence; sometimes these things just happen. But I’m not sure the trial court opinion would have come out the same if it were held today.”
Again, see more from this interview, also about teacher evaluation systems in general, job protections, and the like in the full article here.
Citation: Cohen, R. M. (2016, August 4). Q&A: The economic consequences of eenying teachers tenure. The American Prospect. Retrieved from http://prospect.org/article/qa-economic-consequences-denying-teachers-t…
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