Sean Corcoran: “Teacher Effectiveness on High- and Low-Stakes Tests”

Sean Corcoran

Associate Professor of Education Economics
New York University

A large literature demonstrates that teacher effects on academic achievement are substantial in size. Moreover, this research finds that little of the variation in teacher effectiveness can be explained by observable characteristics such as certification, education, and experience. Motivated by these findings, policymakers have sought to tie teachers' evaluation, pay, and tenure to measures of their "value-added'' on standardized tests. Evidence on school responses to test-based accountability systems, however, suggests that school behaviors can diminish the validity of test score gains associated with such systems. In this paper, we use data from the Houston Independent School District to estimate teacher effects on two separate tests of the same subjects--a "high stakes'' state test used for accountability, and a "low stakes'' audit test. We find that:

• Teacher effects on the high-stakes test vary more than those on the low-stakes test.
• Teachers deemed most effective on the high-stakes test are not necessarily most effective on the audit test.
• Returns to experience differ substantially across the two tests.
• Teacher effects on the low-stakes test persist into later grades to a much greater degree than those on the high-stakes test.