Using Student Performance to Evaluate Teachers

O ver the past 15 years, a growing body of research has demonstrated that teachers are the most important school-based determinant of student achievement. Taking advantage of improved educational data systems that link students to their teachers, this research has used a class of statistical techniques called value-added models to estimate teachers’ impact on their students’ standardized test performance. Such research has also shown that many current teacher evaluation systems, which rely mainly on supervisor judgments, do not adequately reflect variation in teachers’ estimated ability to raise test scores. As a result, there is a growing interest in developing teacher evaluation systems that incorporate value-added estimates of teachers’ effects on student achievement.1 However, systems that incorporate student test scores into teacher evaluations face at least two important challenges. First, they must support valid and reliable inferences about teachers’ contributions to student learning, and, second, they must attempt to include teachers who do not teach subjects or grades that are tested annually. The Center for American Progress, with support from the Bill and Melinda Gates Foundation, asked RAND to review the literature and examine how five educational systems are beginning to approach these challenges.