February 24, 2013
Ezra Klein, the Washington Post’s chief policy wonk, has a fascinating, upbeat interview with Thomas Kane about the evaluation of teachers. Kane is professor of education and economics at the Harvard Graduate School of Education and faculty director of the Center for Education Policy Research.
Money quote: “I think what we showed was that if you combine data from three different sources, from classroom observation, a student survey and a teacher’s past history of achievement gains, controlling in the ways that school districts are now commonly controlling for them, by controlling for students’ baseline test scores, you can identify teachers who cause greater learning to happen, and I can use the word “cause” because we used random assignment.”
This is sophisticated research with encouraging results. Before you say, “but….” read the interview. (And don’t get distracted by the title the Washington Post puts on it; it’s misleading.)
Kane adds, “Do I think these measures will get better? Yes … But relative to the information that we’re giving principals now for making personnel decisions now, and teachers who want to do better, it’d be a huge step forward to combine these three.”
Of course all this just (just?) concerns the K-12 world. In higher education we’re trying to work with (at best!) a one-legged stool. Generally, we do not observe teachers and we do not use valid and reliable measures of student achievement. Given what Kane is saying, shouldn’t we try these?
Towards the end, Klein and Kane discuss a 2012 paper by Raj Chetty, John Friedman and Jonah Rockoff about what difference having good teachers makes in life outcomes. From the abstract, here is the jaw-dropping summary. (VA means value added. A high-VA teacher is a teacher whose students learn more as measured by standardized tests.)
Students assigned to high-VA teachers are more likely to attend college, attend higher- ranked colleges, earn higher salaries, live in higher SES neighborhoods, and save more for retirement. They are also less likely to have children as teenagers. Teachers have large impacts in all grades from 4 to 8. On average, a one standard deviation improvement in teacher VA in a single grade raises earnings by about 1% at age 28. Replacing a teacher whose VA is in the bottom 5% with an average teacher would increase the present value of students’ lifetime income by more than $250,000 for the average classroom in our sample. We conclude that good teachers create substantial economic value and that test score impacts are helpful in identifying such teachers.
No, of course economic consequences are not the only purpose of an education, but these results are stunning. Good teaching matters, and we know how to identify good teaching.