Clarifies the primary questions raised by the use of value-added models (VAM) for measuring teacher effects, reviews the most important recent applications of VAM, and discusses statistical and measurement issues associated with VAM. Does value-added modeling (VAM) demonstrate the importance of teachers to student outcomes? The authors clarify the primary questions raised by VAM for measuring teacher effects, review the most important recent applications of VAM, and discuss a variety of statistical and measurement issues that might affect the validity of VAM inferences. The authors identify numerous possible sources of error and bias in teacher effects and recommend a number of steps for future research into these potential errors.

In our increasingly technological society, improving students' performance in mathematics and science has become a critical challenge. During the 1990s, the National Science Foundation funded a series of Systemic Initiatives designed to change the way these subjects are being taught in schools throughout the country. These initiatives sought to align all aspects of the educational system in support of ambitious curriculum and performance standards, with particular emphasis on teacher training and professional development to promote effective changes in instructional practice.