The motivation for this paper is the authors' recent work on several randomized control trials in which they found the primary result, which averaged across subgroups or sites, to be moderated by demographic or site characteristics. They are led to examine a distinction that the Institute of Education Sciences (IES) makes between "confirmatory"…

This study examines trends in American students' growth trajectories in reading and math achievement over the past three decades. Drawing upon multiple sources of national assessment data, cohort analyses provide new evidence on the stability and change of national academic growth curves. The emerging trends imply a tripartite pattern where…

How many students repeat a grade each year? How do retention rates vary across states and over time? Despite extensive research on the predictors and consequences of grade retention, there is no systematic way to quantify state-level retention rates; even national estimates rely on imperfect proxy measures. We present a conceptually simple…

In the "PIRLS (Progress in International Reading Literacy Study) 2006 Encyclopedia," each participating country, 39 in total, describes its education system and the reading curriculum as it is intended to be taught, and outlines the polices and practices that guide reading instruction and teacher education. This in-depth, qualitative…