Estimating Impacts of Treatment Random Assignment on Classroom Quality in the Head Start Impact Study: The Problem of Missing Data

As a result of the 1998 reauthorization of Head Start, the Department of Health and Human Services conducted a national evaluation of the Head Start program. The goal of Head Start is to improve the school readiness skills of low-income children in the United States. There is a substantial body of experimental and correlational research that has found associations between the quality of children's early childhood classrooms and their subsequent academic success (Pianta, Barnett, Burchinal, & Thornburg, 2009; Raver et al., 2008; 2009; 2011; Zaslow et al., 2010). A particularly important part of evaluating the effectiveness of Head Start is understanding whether the program improves the quality of participants' early learning environments. Results from the original analysis of the classroom quality data from the Head Start Impact Study (U.S. Department of Health and Human Services, 2010) show that randomization to Head Start lead to improvement in the quality of care children received. However, these results are obfuscated by the way in which missing data were handled. The apparent improvements in classroom quality may be due to greater access to formal care settings. To address this problem, the primary objectives of this research are to address the challenges faced when estimating impacts of treatment random assignment on classroom quality within the Head Start Impact Study, to explore how different solutions influence the impact estimates, and to offer methodological solutions. What are the impacts of random assignment to Head Start on measures of classroom quality? Do children who are randomly assigned to Head Start receive higher/better quality care than children who are randomly assigned to the control group? Results confirm that the three types of missing data described here are indeed endogenous to treatment random assignment. Thus, methodological approaches must be used to handle missing data in order to obtain unbiased estimates of impacts of random assignment to Head Start on classroom quality. Tables are appended.