A Think Twice Review of:
Measuring the Impacts of Teachers I (NBER No. 19423) & II (NBER No. 19424)
Think Twice - Apr 10, 2014
Publisher/Think Tank - National Bureau of Economic Research (NBER)
Author(s) - Raj Chetty, John N. Friedman, and Jonah E. Rockoff (both papers)
This NBER working paper - split in two parts - studied the impact of teachers on long-term outcomes using value-added scores. The reports addressed a key question: Are teachers' impacts on students' test scores ("value added") a good measure of their quality? Economists Raj Chetty, John Friedman, & Jonah Rockoff claim in a two-part paper that higher value-added scores for teachers lead to greater economic success for their students later in life. The paper drew widespread media and politicians' attention, including the president's.
Reviewer(s) - Moshe Adler, Columbia University & Empire State College, SUNY
Moshe Adler of the department of Urban Planning at Columbia University and the Harry Van Arsdale, Jr. Center for Labor Studies at Empire State College, SUNY reviewed the reports for the Think Twice think tank review project. In his review Adler found five problems that invalidate the paper's main claim: (1) the paper fails to mention the existence of a crucial conflicting result that was reported in an earlier version of the same paper; (2) the paper claims that there was insufficient data to investigate whether teacher value-added has an effect on income at any age after the age of 28. This claim is untrue; (3) the method used to calculate the effect of teacher value-added on income at age 28 is biased and misleading; (4) the paper makes assumptions that inflate its main result, but the evidence contradicts these assumptions; and (5) the studies that the paper cites in support of its methodology don't actually provide that support.