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Editor’s Note

The Los Angeles Times set off a vigorous debate on the fairness of using “value-added” analysis to judge teacher performance when it announced that it would publish a database of the most effective and least effective teachers in the Los Angeles Unified School District. This article from our archives explains value-added methods and some of their limitations.

Volume 25, Number 2
March/April 2009

An Inexact Science

What are the technical challenges involved in using value-added measures?

An Inexact Science, continued


 
Every year, teachers in Tennessee receive two reports on their students’ academic performance. The first, which details their scores on state accountability tests, is reported publicly and used in school reports on student achievement.

The second report is shared only with the teacher and the principal. That report analyzes the students’ test results based on their past performance and background characteristics to calculate the “value added” by the teacher in terms of student learning. Teachers with high value-added scores improved student performance faster than expected, while those with low scores did less well.

Under state law, the value-added scores may not be used to grant or deny tenure, pay increases, or other rewards. However, principals have used the information to make decisions about professional development, and some districts have used the scores in special initiatives. Chattanooga, for example, offered incentives to teachers with high value-added scores who agreed to teach in low-performing schools.


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D. F. McCaffery, J. R. Lockwood, D. M. Koretz, and L. Hamilton. Evaluating Value Added Models for Teacher Accountability (PDF), Santa Monica, CA: Rand, 2003.

D. Goldhaber and M. Hansen. Assessing the Potential of Using Value-Added Estimates of Teacher Job Performance for Making Tenure Decisions (PDF), Bothell, WA: University of Washington Bothell, Center for Reinventing Public Education, 2008.

D. N. Harris. “Would Accountability based on Teacher Value-Added Be Smart Policy? An Examination of the Statistical Properties and Policy Alternatives.” (PDF) Education Finance and Policy, forthcoming.