The testing effect is a well-known concept referring to gains in learning and retention that can occur when students take a practice test on studied material before taking a final test on the same material. Research demonstrates that students who take practice tests often outperform students in nontesting learning conditions such as restudying,…

The Student Climate and Conservation Congress (SC3) is a joint educational effort between the United States Fish and Wildlife Service and the Green Schools Alliance that aims to develop the next generation of conservation leaders through fostering action competence in youth. Data from SC3 participants was used to investigate four predictors of…

Using meta-analytic techniques, we examined systematically the evidence linking friendship to academically related outcomes, asking: To what extent is friendship related to academic performance and to academically related cognitive skills? Based on 22 studies that yielded 81 effect sizes and 28 independent samples, we examined relations between…

In a meta-analysis, it is important to specify a model that adequately describes the effect-size distribution of the underlying population of studies. The conventional normal fixed-effect and normal random-effects models assume a normal effect-size population distribution, conditionally on parameters and covariates. For estimating the mean overall…

The purpose of this study is to illustrate the multilevel meta-analysis of results from single-subject experimental designs of different types, including AB phase designs, multiple-baseline designs, ABAB reversal designs, and alternating treatment designs. Current methodological work on the meta-analysis of single-subject experimental designs…

Outdoor adventure education (OAE) has a long history of being credited with the personal and social development (PSD) of its participants. PSD is notoriously difficult to measure quantitatively, yet stakeholders demand statistical evidence that given approaches to eliciting PSD are effective in their methods. Rightly or wrongly, many stakeholders…

Replication research is essential to scientific knowledge. Reviews of replication studies often electronically search for "replicat*" as a textword, which does not identify studies that replicate previous research but do not self-identify as such. We examined whether the 83 intervention studies published in six non-categorical research…

Inference ability is considered central to discourse processing and has been shown to be important across models of reading comprehension. To evaluate the impact of inference instruction, a meta-analysis of 25 inference studies in Grades K-12 was conducted. Results showed that inference instruction was effective for increasing students' general…

Despite calls to expand early childhood education (ECE) in the United States, questions remain regarding its medium- and long-term impacts on educational outcomes. We use meta-analysis of 22 high-quality experimental and quasi-experimental studies conducted between 1960 and 2016 to find that on average, participation in ECE leads to statistically…

This review describes a meta-analysis of findings from 50 controlled evaluations of intelligent computer tutoring systems. The median effect of intelligent tutoring in the 50 evaluations was to raise test scores 0.66 standard deviations over conventional levels, or from the 50th to the 75th percentile. However, the amount of improvement found in…

When cluster randomized experiments are analyzed as if units were independent, test statistics for treatment effects can be anticonservative. Hedges proposed a correction for such tests by scaling them to control their Type I error rate. This article generalizes the Hedges correction from a posttest-only experimental design to more common designs…

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disability characterized by symptoms of inattention, hyperactivity and impulsiveness, which may cause impairment in a variety of cognitive, social, behavioral, and emotional domains. Extensive research has been conducted to determine the best course of treatment for…

Individual participant data (IPD) meta-analysis is an increasingly used approach for synthesizing and investigating treatment effect estimates. Over the past few years, numerous methods for conducting an IPD meta-analysis (IPD-MA) have been proposed, often making different assumptions and modeling choices while addressing a similar research…

Attempts have been made to identify behavior patterns peculiar to leadership by many institutions and organizations; also numerous studies have been conducted in this area. Of all these organizations, The Interstate School Leaders Licensure Consortium (ISLLC) identifies the definitive standards of school leadership. Examining these standards in…

Background: Because meta-analyses are increasingly prevalent and cited in the medical literature, it is important that tools are available to assess their methodological quality. When performing an empirical study of the quality of published meta-analyses, we found that existing tools did not place a strong emphasis on statistical and…