The Dependence of Growth-Model Results on Proficiency Cut Scores

States participating in the Growth Model Pilot Program reference individual student growth against “proficiency” cut scores that conform with the original No Child Left Behind Act (NCLB). Although achievement results from conventional NCLB models are also cut-score dependent, the functional relationships between cut-score location and growth results are more complex and are not currently well described. We apply cut-score scenarios to longitudinal data to demonstrate the dependence of state- and school-level growth results on cut-score choice. This dependence is examined along three dimensions: 1) rigor, as states set cut scores largely at their discretion, 2) across-grade articulation, as the rigor of proficiency standards may vary across grades, and 3) the time horizon chosen for growth to proficiency. Results show that the selection of plausible alternative cut scores within a growth model can change the percentage of students “on track to proficiency” by more than 20 percentage points and reverse accountability decisions for more than 40% of schools. We contribute a framework for predicting these dependencies, and we argue that the cut-score dependence of large-scale growth statistics must be made transparent, particularly for comparisons of growth results across states.