Validating Teacher Effects on Students’ Attitudes and Behaviors: Evidence from Random Assignment of Teachers to Students

There is growing interest among researchers, policymakers, and practitioners in identifying teachers who are skilled at improving student outcomes beyond test scores. However, important questions remain about the validity of these teacher effect estimates. Leveraging the random assignment of teachers to classes, I find that teachers have causal effects on their students’ selfreported behavior in class, self-efficacy in math, and happiness in class that are similar in magnitude to effects on math test scores. Weak correlations between teacher effects on different student outcomes indicate that these measures capture unique skills that teachers bring to the classroom. Teacher effects calculated in non-experimental data are related to these same outcomes following random assignment, revealing that they contain important information content on teachers. However, for some non-experimental teacher effect estimates, potentially large and important degrees of bias remain. These results suggest that researchers and policymakers should proceed with caution when using these measures. They likely are more appropriate for low-stakes decisions, such as matching teachers to professional development, than for high-stakes personnel decisions and accountability. Correspondence regarding the paper can be sent to David Blazar at [email protected]; Department of Teaching and Leaning, Policy and Leadership, 2311 Benjamin Building, University of Maryland College of Education, College Park, MD, 20742. I would like to thank Martin West, Thomas Kane, Heather Hill, and anonymous reviewers for their feedback on earlier drafts. The data collection effort described here was supported by the Institute of Education Sciences, U.S. Department of Education, through Grant R305C090023 to the President and Fellows of Harvard College to support the National Center for Teacher Effectiveness. The opinions expressed are those of the author and do not represent views of the Institute or the U.S. Department of Education. Research support came from the Mathematica Policy Research summer fellowship and the Smith Richardson Foundation.