Partially specified correlation matrices (not to be confused with matrices with missing data or EM-correlation matrices) can appear in research settings such as integrative data analyses, quantitative systematic reviews or whenever the study design only allows for the collection of certain variables. Although approaches to fill in these missing…

In causal mediation studies that decompose an average treatment effect into indirect and direct effects, examples of post-treatment confounding are abundant. In the presence of treatment-by-mediator interactions, past research has generally considered it infeasible to adjust for a post-treatment confounder of the mediator-outcome relationship due…

A wide variety of methodological choices and situations can affect the quality of peer nomination measurements but have not received adequate study. This article begins by focusing on systematic nominator missingness as an example of one such situation. We reanalyzed findings from a recent study by Bukowski, Dirks, Commisso, Velàsquez, and Lopez…

Determining the number of factors in exploratory factor analysis is arguably the most crucial decision a researcher faces when conducting the analysis. While several simulation studies exist that compare various so-called factor retention criteria under different data conditions, little is known about the impact of missing data on this process.…

Meta-studies are often conducted on empirical findings obtained from overlapping samples. Sample overlap is common in research fields that strongly rely on aggregated observational data (eg, economics and finance), where the same set of data may be used in several studies. More generally, sample overlap tends to occur whenever multiple estimates…

Purpose of the Study: Missing data are a common problem encountered while implementing measurement instruments. Yet the extent to which reliability, validity, average discrimination and difficulty of the test results are affected by the missing data has not been studied much. Since it is inevitable that missing data have an impact on the…

This article describes the results of an experiment designed to examine the impact of the use and amount of delayed unconditional incentives in a mixed mode (push to web) supplement on response rates, response mode, data quality, and sample bias. The supplement was administered to individuals who participate in the U.S. Panel Study of Income…

This study investigates technical efficiency and productivity for Swedish higher education institutions (HEIs). One identified problem in previous research concerns adjusting efficiency scores for input quality. This problem is avoided using grades from upper-secondary schools. A second problem concerns heterogeneity with respect to subjects and…

Researchers suggest that certain supportive behaviors of mentors could increase the benefits of school-based mentoring for youth. However, the literature contains few validated instruments to measure these behaviors. In our present study, we aimed to construct and validate a tool to measure the supportive behaviors of mentors participating in…

In order to better assist practitioners and better serve persons with autism spectrum disorders (ASD) and their families, it is vital for professionals to systematically evaluate the existing body of literature and synthesize its scientific evidence, so that the efficacy of research can be translated to evidence-based practices (EBPs) (Wheeler,…

Educational researchers commonly use the rule of thumb of "design effect smaller than 2" as the justification of not accounting for the multilevel or clustered structure in their data. The rule, however, has not yet been systematically studied in previous research. In the present study, we generated data from three different models…

Debate is occurring about which result interpretation aides focused on examining the experimental effect should be used in single-subject experimental research. In this study, we examined seven nonoverlap methods and compared results using each method to judgments of two visual analysts. The data sources for the present study were 36 studies…

National average happiness and the difference in happiness between women and men are positively correlated in European countries. This study focuses on this cross-country relationship and tests (1) whether, after controlling for socio-economic factors, the correlation is attributed to their direct relationship, or, alternatively, explained by the…

This paper challenges Hanushek and Woessmann's (2008) contention that the quality and not the quantity of schooling determines a nation's rate of economic growth. I first show that their statistical analysis is flawed. I then show that when a nation's average test scores and average schooling attainment are included in a national income model,…

Background: Mentoring has drawn substantial interest from policymakers, intervention theorists, and those interested in identifying promising and useful evidence-based approaches to interventions for criminal justice and child welfare outcomes (Grossman & Tierney, 1998; Jekliek et al., 2002). Mentoring is one of the most commonly-used…