Technical Methods Report: Estimation and Identification of the Complier Average Causal Effect Parameter in Education RCTs

Randomized control trials (RCTs) in the education field typically examine the intention-to-treat parameter, which is estimated by comparing the mean outcomes of treatment group members to those of the control group. This report examines the identification and estimation of the complier average causal effect (CACE) parameter—the average impact of intervention services on those who comply with their treatment assignments—under clustered RCT designs that are typically used in the education field. The authors used data from ten large-scale RCTs to compare significance findings for the CACE estimator measured in nominal and standard deviation units using the correct variance formulas with those that are typically used in practice. The empirical results indicate that the variance correction terms matter little.