A new PACE policy brief by Douglas N. Harris of the University of Wisconsin, Madison, explores the use of value-added measures and discusses the strengths and weaknesses of value-added assessment, both as a means to assess teachers and as a means to assess schools. Current federal policies do not account for the fact that student outcomes are produced by more than just schools. As a result, they fail to follow what Douglas Harris calls the “Cardinal Rule of Accountability”: hold people accountable for what they can control.
In this policy brief, Douglas Harris explores the problems with attainment measures when it comes to evaluating performance at the school level, and explores the best uses of value-added measures. These value-added measures, Harris writes, are useful for sorting out of school influences from school influences or from teacher performance, giving us overall better performance measures. Value-added measures provide summative assessments of teacher performance. They indicate whether teachers are doing well or not, on one important measure of student performance. But value added is often criticized for not providing information about how to improve. Thus, Harris explores the strengths and limitations of value-added measures and provides guidelines for best uses and practices.