Rothstein, Chetty et al., and (Now) Kane on Bias

Here’s an update to a recent post about research conducted by Berkeley Associate Professor of Economics – Jesse Rothstein.

In Rothstein’s recently released study, he provides evidence that puts the aforementioned Chetty et al. results under a more appropriate light. Rothstein’s charge, again, is that Chetty et al. (perhaps unintentionally) masked evidence of bias in their now infamous VAM-based study, which in turn biased Chetty et al.’s (perpetual) claims that teachers caused effects in student achievement growth over time. These effects, rather, might have been more likely caused by bias given the types of students non-randomly assigned to teachers’ classrooms versus “true teacher effects.”

In addition, while in his study Rothstein replicated Chetty et al.’s overall results using a similar data set, so did Thomas Kane – a colleague of Chetty’s at Harvard who has also been the source of prior VAMboozled! posts here, here, and here. During the Vergara v. California case last summer, the prosecuting team actually used Kane’s (and colleagues’) replication-study results to validate Chetty et al.’s initial results.

However, Rothstein did not replicate Chetty et al.’s findings when it came to bias (the best evidence of this is offered in Rothstein’s study’s Appendix B). Inversely, Kane’s (and colleagues’) study did not, then, have any of the prior year score analyses needed to analyze and assess bias, so the extent to which Chetty et al.’s results were due to bias was then more or less moot.

But after Rothstein released his recent study effectively critiquing Chetty et al. on this point, Kane (and colleagues) released the results Kane presented at the Vergara trial (see here). However, Kane (and colleagues) seemingly released an updated version of “Kane’s” initial results to seemingly counter Rothstein, in support of Chetty. In other words, Kane seems to have released his study (perhaps) more in support of his colleague Chetty than in the name of conducting good, independent research.

Oh the tangled web Chetty and Kane (purportedly) continue to weave.

See also Chetty et al.’s direct response to Rothstein here.

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