Randomized trials are often conducted with separate randomizations across multiple sites such as schools, voting districts, or hospitals. These sites can differ in important ways, including the site's implementation, local conditions, and the composition of individuals. An important question in practice is whether--and under what…

In recent years, governments across the world have increased their investments in early childhood education programs (Britto, Yoshikawa, & Boller, 2011; Engle et al., 2011; Myers, 2006; UNESCO, 2006). This investment in preprimary education reflects the proven value of providing early learning opportunities in promoting later educational…

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…

Mastering basic numeracy and literacy skills is one of the most fundamental goals of education. However, it is estimated that 250 million primary-school-age children lack basic reading, writing and math skills (UN, 2013). Children living in war and poverty stricken countries are among the least likely to attain those basic goals. The United States…