Evaluating Value-Added Models for Teacher Accountability

Value-added modeling (VAM) to estimate school and teacher effects is currently of considerable interest to researchers and policymakers. Recent reports suggest that VAM demonstrates the importance of teachers as a source of variance in student outcomes. Policymakers see VAM as a possible component of education reform through improved teacher evaluations or as part of test-based accountability. They are particularly intrigued by VAM because of the view that its complex statistical techniques can provide estimates of the effects of teachers and schools that are not distorted by the powerful effects of such noneducational factors as family background. This monograph attempts to clarify the primary questions raised by the use of VAM for measuring teacher effects, review the most important recent applications of VAM, and discuss a variety of the most important statistical and measurement issues that might affect the validity of VAM inferences.

go to the website:  http://www.rand.org/pubs/monographs/MG158/