The Problem With “Proficiency”: Limitations of Statistics and Policy Under No Child Left Behind

The Percentage of Proficient Students (PPS) has become a ubiquitous statistic under the No Child Left Behind Act. This focus on proficiency has statistical and substantive costs. The author demonstrates that the PPS metric offers only limited and unrepresentative depictions of large-scale test score trends, gaps, and gap trends. The limitations are unpredictable, dramatic, and difficult to correct in the absence of other data. Interpretation of these depictions generally leads to incorrect or incomplete inferences about distributional change. The author shows how the statistical shortcomings of these depictions extend to shortcomings of policy, from exclusively encouraging score gains near the proficiency cut score to shortsighted comparisons of state and national testing results. The author proposes alternatives for large-scale score reporting and argues that a distribution-wide perspective on results is required for any serious analysis of test score data, including “growth”-related results under the recent Growth Model Pilot Program.