The purpose of this research was to compare the performances of the Fixed Effect Model (FEM) and the Random Effects Model (REM) in the meta-analysis studies conducted through 5, 10, 20 and 40 studies with an outlier and 4, 9, 19 and 39 studies without an outlier in terms of estimated common effect size, confidence interval coverage rate and…

There is a long-standing controversy over the relationship between psychopathology and creativity. Yet there is a lack of evidence regarding the relationship between common psychopathologies and indicators of little-c, or every day, creativity among laypeople. To make sense of this connection, we conducted a meta-analysis using 89 studies to…

Researchers are strongly encouraged to accompany the results of statistical tests with appropriate estimates of effect size. For 2-group comparisons, a probability-based effect size estimator ("A") has many appealing properties (e.g., it is easy to understand, robust to violations of parametric assumptions, insensitive to outliers). We review…

This study examined the effects of differential grading in science, technology, engineering, and mathematics (STEM) and non-STEM fields over eight consecutive semesters. Using data from 62,122 students at 26 four-year postsecondary institutions, students were subdivided by institutional admission selectivity levels, gender, and student major…

In this study, the authors examined whether individuals with disabilities report higher levels of trauma symptoms than their nondisabled counterparts. Based on trauma theory and prior research regarding the incidence rate of posttraumatic stress disorder, the authors hypothesized that individuals with disabilities would report higher levels of…