"Attrition" is the loss of sample during the course of a study. It occurs when individuals initially randomly assigned in a study are not included when researchers examine the outcome of interest. Attrition is a common issue in education research, and it occurs for many reasons. The What Works Clearinghouse (WWC) is an initiative of the…

Objective: There is substantial evidence that poorly designed and reported research can mislead decision making in clinical care. This review investigates the methodological quality of Swedish trials of a wide array of psychological and social interventions. Method: The review includes 302 articles published in peer-reviewed journals during…

In the "individually randomized group treatment" (IRGT) experimental design, individuals are first randomly assigned to a treatment arm or a control arm, but then within each arm, are grouped together (e.g., within classrooms/schools, through shared case managers, in group therapy sessions, through shared doctors, etc.) to receive…

Randomized experiments provide unbiased estimates of treatment effects, but are costly and time consuming. We demonstrate how a randomized experiment can be leveraged to measure selection bias by conducting a subsequent observational study that is identical in every way except that subjects choose their treatment--a quasi-doubly randomized…

Improving academic, behavioural, and social outcomes of students through empirical research has been a firm commitment among researchers, policy-makers, and other professionals in education across Europe and the United States (U.S.). To assist in building scientific evidences, executive bodies such as the European Commission and the Institute for…

Multisite trials, in which individuals are randomly assigned to alternative treatment arms within sites, offer an excellent opportunity to estimate the cross-site average effect of treatment assignment (intent to treat or ITT) "and" the amount by which this impact varies across sites. Although both of these statistics are substantively…

There are few high-quality studies using randomized controlled trials (RCTs) in the adventure and wilderness therapy literature. Thus, a unison call is heard for more such studies to be carried out. This article presents a Norwegian wilderness therapy research project that planned to incorporate this "gold standard" that is regarded as…

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…

This publication contains 12 (A3 open-out) poster-style reports of teacher experimental research. The style of presentation parallels the type of preliminary reporting common at academic conferences and postgraduate events. At the same time, it aims to act as a form of short primer to introduce teachers to the basic options that there are when…