Using a sample of 70,399 published p-values from 192 meta-analyses, we empirically estimate the counterfactual distribution of p-values in the absence of any biases. Comparing observed p-values with counterfactually expected p-values allows us to estimate how many p-values are published as being statistically significant when they should have been…

Single-case design (SCD) is a quantitative experimental technique in which participants serve as their own control. The use of an effect size in SCD allows evaluation of outcomes as well as comparison of outcomes via meta-analyses. Characteristics of SCD research make the selection of an appropriate effect size complicated. Additionally, there are…

Meta-analyses play an instrumental role in informing second language (L2) theory and practice. However, current (i.e., classic) approaches to meta-analysis are limited in their ability to do so because they often fail to capture the complexity inherent in primary studies' research designs. As we argue in this article, when complex L2 studies are…

Differences in effect sizes between researcher developed (RD) and independently developed (ID) outcome measures are widely documented but poorly understood in education research. We conduct a meta-analysis using item-level outcome data to test potential mechanisms that explain differences in effects by RD or ID outcome type. Our analysis of 45…

Children's fears have received scholarly attention for well over 50 years. A considerable amount of literature has focused on such fear variables as fear intensity and fear prevalence scores and age and gender differences. We used meta-analysis to systematically review the findings related to gender differences in children's fear intensity scores…

Collecting data for an individual participant data meta-analysis (IPDMA) project can be time consuming and resource intensive and could still have insufficient power to answer the question of interest. Therefore, researchers should consider the power of their planned IPDMA before collecting IPD. Here we propose a method to estimate the power of a…

Background/Context: The reckoning with racial injustice and growing inequality that have become hallmarks of the early 2020s in the United States has implications for impact analysis and the evidence it produced for public policy decision-making. Various researchers have highlighted the shortcomings that impact analyses have when estimating the…

Mathematical problem posing, generally defined as the process of interpreting given situations and formulating meaningful mathematical problems, is academically important, and thus several interventions have been used to enhance this competence among students and teachers. Yet little is known about the interventions' various components and their…

We have entered an era in which scientific evidence increasingly informs research practice and policy. As there is an exponential increase in the use of single-case experimental designs (SCEDs) to evaluate intervention effectiveness, there is accumulating evidence available for quantitative synthesis. Consequently, there is a growing interest in…

Why we need better reports of teacher professional development interventions for finding out what works where: Worldwide, billions of dollars are invested yearly in the professional development of in-service teachers ($14 billion in the USA alone, as of 2014; Bill & Melinda Gates Foundation, 2014). This makes the question of what effects TPD…

Although most gifted education programs have included undergraduate research (UGR) in their training plans, scholars have not reached a consensus on UGR's effectiveness, especially for gifted college students. With a sample of 7460 students from 15 studies conducted worldwide during 1985-2022, this study explores the relationship between research…