Multi-site randomized controlled trials (RCTs) provide unbiased estimates of the average impact in the study sample. However, their ability to accurately predict the impact for individual sites outside the study sample, to inform local policy decisions, is largely unknown. To extend prior research on this question, we analyzed six multi-site RCTs…

Traditionally, cluster randomized controlled trials are analyzed with the average intervention effect of interest. However, in populations that contain higher degrees of heterogeneity or variation may differ across different values of a covariate, which may not be optimal. Within education and social science contexts, exploring the variation in…

Parenting programs have been shown to be effective in preventing and reducing externalising problems in young children. Despite their efficacy, the low rate of initial parental engagement in these programs is a major challenge for clinicians and researchers. Few studies have examined factors associated with rates of initial engagement in parenting…

This article examines the implementation, participation rates, and potential determinants of participation in the digital addiction prevention program "ready4life." A two-arm cluster-randomized trial recruited German vocational students via class-based strategies. Intervention group received 16 weeks of in-app coaching; the control group…

High-quality preschool programs are heralded as an effective policy tool to promote the development and life-long wellbeing of children from low-income families. Yet evaluations of recent preschool programs produce puzzling findings, including negative impacts, and divergent, weaker results than were shown in demonstration programs implemented in…

Background: This systematic review investigated the state of intervention science on programs that promote healthy intimate relationship skills and sexual health for autistic youth (i.e., healthy intimacy). Methods: Using PRISMA guidelines, we reviewed randomized controlled trials (RCTs) published in 2010 or later that enrolled [less than or equal…

Background: In children with a cleft palate with or without a cleft lip (CP±L), some evidence exists for superior results of high-intensity speech intervention (HISI) compared with low-intensity speech intervention (LISI) on speech and health-related quality of life (HRQoL). However, the existing research often involves small sample sizes.…

The purpose of this article is to examine the application of randomized controlled trial (RCT) methodology for determining the efficacy of school-based interventions in general and special education. In education science, RCTs are widely acknowledged as the gold standard of efficacy research, with other methodologies relegated to a lower level of…

Power in multilevel models remains an area of interest to both methodologists and substantive researchers. In two-level designs, the total sample is a function of both the number of level-2 (e.g., schools) clusters and the average number of level-1 (e.g., classrooms) units per cluster. Traditional multilevel power calculations rely on either the…

Cluster randomized control trials often incorporate a longitudinal component where, for example, students are followed over time and student outcomes are measured repeatedly. Besides examining how intervention effects induce changes in outcomes, researchers are sometimes also interested in exploring whether intervention effects on outcomes are…

Plausible competing developmental models show similar or identical structural equation modeling model fit indices, despite making very different causal predictions. One way to help address this problem is incorporating outside information into selecting among models. This study attempted to select among developmental models of children's early…

Meta-analyses are systematic summaries of research that use quantitative methods to find the mean effect size (standardized mean difference) for interventions. Critics of meta-analysis point out that such analyses can conflate the results of low- and high-quality studies, make improper comparisons and result in statistical noise. All these…

This study introduces a novel approach for conducting Systematic Literature Reviews(SLRs) by incorporating a unique mixed-methods design into the well-established SLR process. The proposed approach, identified as Mixed-Methods Based Systematic Literature Review (MMB-SLR), not only provides researchers with a broader perspective on their research…

Noncompliance to treatment assignment is widespread in randomized trials and presents challenges in causal inference. In the presence of noncompliance, the most commonly estimated effect of treatment assignment, also known as the intent-to-treat (ITT) effect, is biased. Of interest in this setting is the complier average causal effect (CACE), the…

Cluster randomized trials (CRTs) are commonly used to evaluate educational interventions, particularly their effectiveness. Recently there has been greater emphasis on using these trials to explore cost-effectiveness. However, methods for establishing the power of cluster randomized cost-effectiveness trials (CRCETs) are limited. This study…