Precision Gains from Publically Available School Proficiency Measures Compared to Study-Collected Test Scores in Education Cluster-Randomized Trials

This paper compares the precision gains from adjusting impact estimates for student-level pretest scores (which can be costly to collect) with the gains associated with using publically available school-level proficiency data (available at low cost), using data from five large-scale randomized control trials conducted for the U.S. Department of Education’s Institute of Education Sciences. On average, adjusting for school-level proficiency does not increase statistical precision as well as student-level baseline test scores. The number of schools included in studies would have to nearly double to compensate for the loss in precision of using school-level instead of student-level data.