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 19 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.

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

Eric S. Taylor and John H. Tyler
National Bureau of Economic Research
March 2011

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