Publications & Resources
Metric-Free Measures of Test Score Trends and Gaps with Policy-Relevant Examples
Andrew D. Ho and Edward H. Haertel
Problems of scale typically arise when comparing test score trends, gaps, and gap trends across different tests. To overcome some of these difficulties, we can express the difference between the observed test performance of two groups with graphs or statistics that are metric-free (i.e., invariant under positive monotonic transformations of the test score scale). In a series of studies broken into three parts, we develop a framework for the application of metric-free methods to routine policy questions. The first part introduces metric-free methodology and demonstrates the advantages of these methods when test score scales do not have defensible interval properties. The second part uses metric-free methods to compare gaps in Hispanic-White achievement in California across four testing programs over a 7-year period. The third part uses metric-free methods to compare trends for “high-stakes” State Reading test scores to State score trends on the National Assessment of Educational Progress from 2002 to 2003. As a whole, this series of studies represents an argument for the usefulness of metric-free methods for quantifying trends and gaps and the superiority of metric-free methods for comparing trends and gaps across tests with different score scales.
Ho, D., & Haertel, E. H. (2006). Metric-free measures of test score trends and gaps with policy-relevant examples (CSE Report 665). Los Angeles: University of California, Los Angeles, National Center for Research on Evaluation, Standards, and Student Testing (CRESST).