Nber Working Paper Series Estimating Teacher Impacts on Student Achievement: an Experimental Evaluation

We used a random-assignment experiment in Los Angeles Unified School District to evaluate various non-experimental methods for estimating teacher effects on student test scores. Having estimated teacher effects during a pre-experimental period, we used these estimates to predict student achievement following random assignment of teachers to classrooms. While all of the teacher effect estimates we considered were significant predictors of student achievement under random assignment, those that controlled for prior student test scores yielded unbiased predictions and those that further controlled for mean classroom characteristics yielded the best prediction accuracy. In both the experimental and non-experimental data, we found that teacher effects faded out by roughly 50 percent per year in the two years following teacher assignment. Thomas J. Kane Harvard Graduate School of Education Gutman Library, Room 455 Appian Way Cambridge, MA 02138 and NBER [email protected] Douglas O. Staiger Dartmouth College Department of Economics HB6106, 301 Rockefeller Hall Hanover, NH 03755-3514 and NBER [email protected]