Teacher Quality in Educational Production: Tracking, Decay, and Student Achievement
Growing concerns over the achievement of U.S. students have led to proposals to reward good teachers and penalize (or fire) bad ones. The leading method for assessing teacher quality is "value added" modeling (VAM), which decomposes students' test scores into components attributed to student heterogeneity and to teacher quality. Implicit in the VAM approach are strong assumptions about the nature of the educational production function and the assignment of students to classrooms. In this paper, I develop falsification tests for three widely used VAM specifications, based on the idea that future teachers cannot influence students' past achievement. In data from North Carolina, each of the VAMs' exclusion restrictions are dramatically violated. In particular, these models indicate large "effects" of 5th grade teachers on 4th grade test score gains. I also find that conventional measures of individual teachers' value added fade out very quickly and are at best weakly related to long-run effects.
Earlier versions of this paper circulated under the title "Do Value Added Models Add Value?" I am grateful to Nathan Wozny and Enkeleda Gjeci for exceptional research assistance. I thank Orley Ashenfelter, Henry Braun, David Card, Henry Farber, Bo Honor, Brian Jacob, Tom Kane, Larry Katz, Alan Krueger, Sunny Ladd, David Lee, Lars Lefgren, Austin Nichols, Amine Ouazad, Mike Rothschild, Cecilia Rouse, Diane Schanzenbach, Eric Verhoogen, Tristan Zajonc, anonymous referees, and conference and seminar participants for helpful conversations and suggestions. I also thank the North Carolina Education Data Research Center at Duke University for assembling, cleaning, and making available the confidential data used in this study. Financial support was generously provided by the Princeton Industrial Relations Section and Center for Economic Policy Studies and the U.S. Department of Education (under grant R305A080560). The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.
Jesse Rothstein, 2010. "Teacher Quality in Educational Production: Tracking, Decay, and Student Achievement," The Quarterly Journal of Economics, MIT Press, vol. 125(1), pages 175-214, February. citation courtesy of