The Effect of Evaluation on Performance: Evidence from Longitudinal Student Achievement Data of Mid-career Teachers

As states and districts seek to overhaul teacher-evaluation systems, this NBER paper answers a salient question: Do evaluations actually improve a teacher’s performance? That’s one hope of reformers and unions alike—that clear and regular feedback will help instructors improve their craft. Based on eight years of data from Cincinnati’s Teacher Evaluation System (TES), the answer is yes—in math, anyway. TES is an evaluation system that uses periodic, unannounced classroom observations coupled with student-work portfolios. For this report, researchers examined data from 2003-04 to 2009-10 to ascertain the impact of TES on mid-career teachers (those in the system for five to nineteen years). Building on performance-evaluation research, these analyses looked not just at any immediate improvements incurred during a teacher’s evaluation period, but at the long-term impacts resulting from participation in TES itself. They do this by comparing achievement of students taught before teacher participation in TES with student achievement during or after TES participation, while also controlling for students’ prior achievement, teacher experience, and relevant demographic variables. Though there were no significant differences found in reading, teacher performance in math improved both during the evaluation period and afterwards. For example, a teacher whose pupils had typically scored in the 50th percentile on math tests before being evaluated begins to see results in the 55th percentile range in the years after evaluation. Teachers who scored in the lowest quartile on their evaluations showed the greatest improvements. As we rethink teacher evaluation, these are promising findings indeed. But be forewarned: A system like TES comes with a lofty price tag—roughly $7,500 for each teacher evaluated (over the course of the six studied years). If districts or states plan on taking it to scale, some financial juggling will be in order.

Eric S. Taylor and John H. Tyler, “The Effect of Evaluation on Performance: Evidence from Longitudinal Student Achievement Data of Mid-career Teachers,” (Cambridge, MA: National Bureau of Economic Research, March 2011).