Multi-site randomized controlled trials (RCTs) provide unbiased estimates of the average impact in the study sample. However, their ability to accurately predict the impact for individual sites outside the study sample, to inform local policy decisions, is largely unknown. To extend prior research on this question, we analyzed six multi-site RCTs…

Applied researchers are increasingly interested in whether and how treatment effects vary in randomized evaluations, especially variation not explained by observed covariates. We propose a model-free approach for testing for the presence of such unexplained variation. To use this randomization-based approach, we must address the fact that the…

Prevent-Teach-Reinforce for Young Children (PTR-YC) is a standardized model of positive behavior support designed to deliver individualized interventions for preschool-aged children with severe and persistent challenging behaviors. A randomized controlled trial was conducted to compare effects of PTR-YC with those of a "business as…

Although extensive research exists on vocabulary instruction during book reading in preschool classroom, comparatively little research has been conducted on vocabulary exposure in classroom play contexts and child vocabulary outcomes. The purpose of this study was to examine Head Start teacher and child vocabulary use in dyadic play sessions and…

Background: We tested the effectiveness of the Go Wild With Fruits and Veggies! (GWWFV) Extension curriculum on increasing fruit and vegetable (FV) intake of third graders. Methods: An intervention study was used testing self-reported FV intake pre/post GWWFV. Recruited schools were randomized to control (12 schools, N = 369, third grade children)…

Guided by the social cognitive theory, this randomized controlled trial tested the "Make a Move," a provider-led intervention for Head Start parents aimed to produce changes in the outcomes of knowledge, attitude, and behavior of physical activity and healthy eating. Participants were parents of children ages 3-5 years enrolled in a Head…

This study seeks to answer the following question: Are impacts on Head Start classroom quality associated with impacts of Head Start on children's learning and development? This study employs a variety of descriptive and quasi-experimental methods to explore the role of classroom quality as a mediator or mechanism of Head Start impacts. This…

Studies of small-scale "model" early-childhood programs show that high-quality preschool can have transformative effects on human capital and economic outcomes. Evidence on the Head Start program is more mixed. Inputs and practices vary widely across Head Start centers, however, and little is known about variation in effectiveness within…