As Ohio transitions to a next-generation accountability system, educators must come to terms with student-growth models. Within the past year, the Buckeye State has introduced three new indicators of school performance that gauge the academic growth of student subgroups. These new indicators stand alongside a school’s growth performance for all of its tested students. Furthermore, the state now requires districts to implement principal and teacher evaluations, half of which are presently based on student-growth measures.
In view of the growing use of student growth in accountability, Ohio’s policymakers and educators should consult A Practitioner’s Guide to Growth Models. The authors of this must-read report provide a clear description of the seven growth models available—from the very rudimentary to the extraordinarily complex—and helpfully contrast the various models from both a statistical and applied perspective.
Of the seven growth models presented, there are two models that states are incorporating into their accountability systems: student-growth percentiles, or SGP (used in Colorado and Massachusetts, for example), and value-added, or VAM (used in Ohio and Pennsylvania). The key takeaways from this report are as follows:
VAM asks a different policy question than SGP.
According to the report, SGP does two things well—it describes and predicts student growth. Growth description unpacks “how much growth” a student group has made (e.g., classroom or school), while growth prediction gets at “growth to where” (i.e., to a proficiency standard) for a group of students. VAM, on the other hand, neither describes nor...