Simulating the Effects of Test Score Reliability and Dimensionality on Teacher Value-Added Scores and Inferences

• In Event: 32.082 - Roundtable Session 11
  In Roundtable Session: 32.082-10 - Actionable Knowledge? Continuing the Debate on Value-Added Approaches to School Accountability

Abstract

The present study examined the bias produced in estimating value-added scores when there are violations to: (a) the assumption of unidimensionality in the measurement model used to estimate student achievement scores, and (b) the assumption that control variables are free of measurement error in the statistical models used to estimate value-added scores. The results showed that value-added scores were differentially biased by variations in the properties of the student achievement tests used to derive the value-added scores. Both bias in the estimation of value-added scores, and the consistency of teachers’ estimated relative effectiveness were most sensitive to variations in the specification of test dimensionality. The results strongly caution against the use of value-added scores to make high-stakes decisions about teachers.

Author

• Danielle Nicole Dupuis, University of Minnesota