The field of education is increasingly committed to adopting evidence-based practices. Although randomized experimental designs provide strong evidence of the causal effects of interventions, they are not always feasible. For example, depending upon the research question, it may be difficult for researchers to find the number of children necessary…

This systematic review of the relationships between principal characteristics and student achievement was created for educators, administrators, policy-makers, and other individuals interested in a comprehensive catalogue of research on relations between principal characteristics and student achievement. It synthesizes what is known about…

As evidence-based reform becomes increasingly important in educational policy, it is becoming essential to understand how research design might contribute to reported effect sizes in experiments evaluating educational programs. The purpose of this study was to examine how methodological features such as types of publication, sample sizes, and…

Systematic reviews and meta-analysis are techniques for synthesizing primary empirical studies to produce a summary of effects. To facilitate this goal, the Campbell Collaboration (C2) supports reviews within the disciplines of crime and justice, education, international development, and social welfare. At the annual Campbell Colloquium, experts…

Charter schools are largely viewed as a major innovation in the public school landscape, as they receive more independence from state laws and regulations than do traditional public schools, and are therefore more able to experiment with alternative curricula, pedagogical methods, and different ways of hiring and training teachers. Unlike…

This report presents results from a new quantitative synthesis of research on the effectiveness and validity of test accommodations for English language learners (ELLs) taking large-scale assessments. In 2006, the Center on Instruction published a review of the literature on test accommodations for ELLs titled "Practical Guidelines for the…

The objective of this report is to review studies that report language and literacy outcomes associated with preschool curriculum-based interventions. Results from studies reporting on interventions targeting preschool children from low-income families were included regardless of the specific type of program. Although the majority of preschool…