When designing cluster-randomized trials (CRTs), one important consideration is determining the proper sample sizes across levels and treatment conditions to cost-efficiently achieve adequate statistical power. This consideration is usually addressed in an optimal design framework by leveraging the cost structures of sampling and optimizing the…

Meta-analyses of treatment effects in randomized control trials are often faced with the problem of missing information required to calculate effect sizes and their sampling variances. Particularly, correlations between pre- and posttest scores are frequently not available. As an ad-hoc solution, researchers impute a constant value for the missing…

Binary outcomes are often analyzed in cluster randomized trials (CRTs) using logistic regression and cluster robust standard errors (CRSEs) are routinely used to account for the dependent nature of nested data in such models. However, CRSEs can be problematic when the number of clusters is low (e.g., < 50) and, with CRTs, a low number of…

When studies use different scales to measure continuous outcomes, standardised mean differences (SMD) are required to meta-analyse the data. However, outcomes are often reported as endpoint or change from baseline scores. Combining corresponding SMDs can be problematic and available guidance advises against this practice. We aimed to examine the…

Conventionally, regression discontinuity analysis contrasts a univariate regression's limits as its independent variable, "R," approaches a cut point, "c," from either side. Alternative methods target the average treatment effect in a small region around "c," at the cost of an assumption that treatment assignment,…

This article describes the analysis of regression-discontinuity designs (RDDs) using the R packages rdd, rdrobust, and rddtools. We discuss similarities and differences between these packages and provide directions on how to use them effectively. We use real data from the Carolina Abecedarian Project to show how an analysis of an RDD can be…

The aim of the study was to conduct a randomized control trial of a targeted, facilitated, test anxiety intervention for a group of adolescent students, and to examine the mediating role of uncertain control. Fifty-six participants (male = 19, white = 21, mean age = 14.7 years) were randomly allocated to an early intervention or wait-list control…

To assess the direct and indirect effect of an intervention, multilevel 2-1-1 studies with intervention randomized at the upper (class) level and mediator and outcome measured at the lower (student) level are frequently used in educational research. In such studies, the mediation process may flow through the student-level mediator (the within…

The primary technique that many researchers use to analyze data from randomized control trials (RCTs)--detecting the average treatment effect (ATE)--imposes assumptions upon the data that often are not correct. Both theory and past research suggest that treatments may have significant impacts on subgroups even when showing no overall effect.…

Despite recent interest in flipped classrooms, rigorous research evaluating their effectiveness is sparse. In this study, the authors implement a randomized controlled trial to evaluate the effect of a flipped classroom technique relative to a traditional lecture in an introductory undergraduate econometrics course. Random assignment enables the…

The Louisiana Scholarship Program (LSP) offers publicly funded vouchers to students in low-performing schools with family income no greater than 250% of the poverty line, allowing them to enroll in participating private schools. Initially established in 2008 as a pilot program in New Orleans, the LSP was expanded statewide in 2012. This article…

This study explores preliminary results from a pedagogical intervention designed to improve instruction for all students, particularly emergent bilinguals in the United States (or English language learners). The study is part of a larger efficacy randomized controlled trial (RCT) of the Instructional Conversation (IC) pedagogy for improving the…

Looked-after children and young people (LACYP) are educationally disadvantaged compared to the general population. A systematic review was conducted of randomised controlled trials evaluating interventions aimed at LACYP aged =18 years. Restrictions were not placed on delivery setting or delivery agent. Intervention outcomes were: academic skills;…