Do Typical RCTs of Education Interventions Have Sufficient Statistical Power for Linking Impacts on Teacher Practice and Student Achievement Outcomes?

For randomized controlled trials (RCTs) of education interventions, estimates of associations between student and mediating teacher practice outcomes can help examine the extent to which the data support the study's conceptual model. They can also identify mediators most associated with student learning. This article develops statistical power formulas for such exploratory analyses under clustered school-based RCTs using ordinary least squares and instrumental variable estimators and uses the formulas to conduct a simulated power analysis.