A growing body of research recognizes the critical role of the school principal, demonstrating that school principals' effects on student outcomes are second only to those of teachers. Yet policy makers have often paid little attention to principals, choosing instead to focus policy reform on teachers. In the last decade, this pattern has shifted…

To address gaps in achievement between more- and less-affluent students, states and districts need to ensure that high-poverty students and schools have equitable access to educational resources. Traditionally, assessments of resource equity have focused on per-pupil expenditures and more proximal inputs, such as teacher credentials and class…

Fixed effects models are often useful in longitudinal studies when the goal is to assess the impact of teacher or school characteristics on student learning. In this article, I introduce an alternative procedure: adaptive centering with random effects. I show that this procedure can replicate the fixed effects analysis while offering several…

The ability of school (or teacher) value-added models to provide unbiased estimates of school (or teacher) effects rests on a set of assumptions. In this article, we identify six assumptions that are required so that the estimands of such models are well defined and the models are able to recover the desired parameters from observable data. These…

Annual student testing may make it possible to measure the contributions to student achievement made by individual teachers. But would these "teacher value-added" measures help to improve student achievement? I consider the statistical validity, purposes, and costs of teacher value-added policies. Many of the key assumptions of teacher value added…

The purpose of this study was to evaluate the sensitivity of growth and value-added modeling to the way an underlying vertical score scale has been created. Longitudinal item-level data were analyzed with both student- and school-level identifiers for the entire state of Colorado between 2003 and 2006. Eight different vertical scales were…

This article develops a model for longitudinal student achievement data designed to estimate heterogeneity in teacher effects across students of different achievement levels. The model specifies interactions between teacher effects and students' predicted scores on a test, estimating both average effects of individual teachers and interaction…

Nonrandom assignment of students to teachers can bias value-added estimates of teachers' causal effects. Rothstein (2008, 2010) shows that typical value-added models indicate large counterfactual effects of fifth-grade teachers on students' fourth-grade learning, indicating that classroom assignments are far from random. This article quantifies…

Value-added indicators are now a central part of school accountability in England, and value-added information is routinely used in school improvement at both the national and the local levels. This article describes the value-added models that are being used in the academic year 2007-8 by schools, parents, school inspectors, and other…

This article considers potential impediments to the estimation of teacher quality caused primarily by the purposeful behavior of families, administrators, and teachers. The discussion highlights the benefits of accounting for student and school differences through a value-added modeling approach that incorporates a student's history of family,…

The utility of value-added estimates of teachers' effects on student test scores depends on whether they can distinguish between high- and low-productivity teachers and predict future teacher performance. This article studies the year-to-year variability in value-added measures for elementary and middle school mathematics teachers from five large…