There are three primary measures of teaching performance: student test-based measures (i.e., value added), classroom observations, and student surveys. Although all three types of measures could be biased by unmeasured traits of the students in teachers' classrooms, prior research has largely...

In a widely cited study, Chetty, Friedman, and Rockoff (2014a; hereafter CFR) evaluate the degree of bias in teacher value-added estimates using a novel "teacher switching" research design with data from New York City. They conclude that there is little to no bias in their estimates. Using the same...