When Hillary Clinton wanted to talk to an esteemed researcher on social mobility, she called Raj Chetty, a Stanford economics professor, a recipient of a MacArthur “Genius” Fellowship, and a winner of the John Bates Clark medal, given to the best American economist under age 40. At Clinton’s request, Chetty flew to her Manhattan office to spend hours going over his research. Clinton then cited his work by name.
When Clinton wanted to talk to an esteemed researcher on teachers, she apparently did NOT call Raj Chetty. If Clinton had talked to Chetty about this issue, she might have learned about his work linking value-added measurement (VAM) scores of teachers to their students’ long-term life outcomes like teen pregnancy rates, college attendance, and early-career earnings. But rather than embracing these findings, Clinton directly refuted them at an AFT roundtable last week:
I have for a very long time also been against the idea that you tie teacher evaluation and even teacher pay to test outcomes. There’s no evidence. There’s no evidence. Now, there is some evidence that it can help with school performance. If everybody is on the same team and they’re all working together, that’s a different issue, but that’s not the way it’s been presented…
Clinton and Chetty are both busy people, so maybe they haven’t had time to connect about education yet. But her “no evidence” refrain is simply wrong. She could have learned this by reading the 5-page summary of evidence Chetty compiled in 2014 with John Friedman and Jonah Rockoff, which concludes that:
…VAM estimates provide information about the causal impacts of teachers on their students’ test score growth. This includes evidence from four separate studies that have directly tested whether VAMs measure correlation or causation… All four of these studies reach the same conclusion: VAMs that control for students’ lagged test scores primarily capture teachers’ causal effects rather than correlations due to other factors not captured in the model. To our knowledge, there is no experimental or quasi-experimental study to date that reaches the opposite conclusion.
The actual implementation of new teacher evaluation systems incorporating student growth is certainly complicated, and there are challenges but also some bright spots and early lessons. I get that we’re in the midst of campaign season and candidates will make overly bold statements. But we should expect policymakers to study and learn from the latest developments in research and practice, not just blindly repeat outdated talking points. So here’s hoping Clinton reconsiders the “no evidence” refrain and consults with Raj Chetty on all of his work, not just some of it.