In connection with the Omnibus Appropriations Act, 2009, GAO (Government Accountability Office) was required to study the What Works Clearinghouse (WWC), a federal source of evidence about effective education practices. Operating through a 5-year contract awarded by the U.S. Department of Education's Institute of Education Sciences (IES), the WWC…

Previous work on statistical power has discussed mainly single-level designs or 2-level balanced designs with random effects. Although balanced experiments are common, in practice balance cannot always be achieved. Work on class size is one example of unbalanced designs. This study provides methods for power analysis in 2-level unbalanced designs…

Problem-based learning (PBL) is a teaching/learning strategy through which students learn course content by solving real-world problems associated with the course material. Although the benefits of PBL have been amply demonstrated in the medical field and other selected subject areas, few studies have examined PBL's potential contributions in…

Background: Whereas preventive interventions for depressed mothers and their infants have yielded positive short-term outcomes, few studies have examined their long-term effectiveness. The present follow-up of a randomised controlled trial (RCT) is one of the first to examine the longer-term effects of an intervention for mothers with postpartum…

The "Expressive Vocabulary Test" (EVT) has recently been found culturally fair for an economically mixed sample of African American children, and others have argued that it is fairer for such participants than the "Peabody Picture Vocabulary Test-III" (PPVT-III). In this study, the authors sought to replicate these findings…

A new line of research has emerged that examines the prevalence rates of mixed methods within disciplines in the social/behavioral sciences. Research presented in this article is unique in that it examines prevalence rates across multiple disciplines using an established cross-disciplinary classification scheme. Results indicate that there are…

This manual provides guidance and documentation for users of the longitudinal kindergarten-fourth grade (K-4) public-use data file of the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011), which includes the first release of the public version of the third-grade data. This manual mainly provides information specific…

This paper seeks to investigate the extent of influence of corporate (or organisational) responsibility on university students' career decision-making. It reports on a pilot study conducted at the University of Sydney which aims to: explore students' ethical, professional and social understanding regarding corporate responsibility; determine the…

Monte Carlo simulations with 20,000 replications are reported to estimate the probability of rejecting the null hypothesis regarding DIF using SIBTEST when there is DIF present and/or when impact is present due to differences on the primary dimension to be measured. Sample sizes are varied from 250 to 2000 and test lengths from 10 to 40 items.…

A number of statistical methods exist for the detection of differential item functioning (DIF). The performance of DIF methods has been widely studied and generally found to be effective in the detection of both uniform and nonuniform DIF. Anecdotal reports suggest that these techniques may too often incorrectly detect the presence of one type of…

Incomplete or missing data is a common problem in almost all areas of empirical research. It is well known that simple and ad hoc methods such as complete case analysis or mean imputation can lead to biased and/or inefficient estimates. The method of maximum likelihood works well; however, when the missing data mechanism is not one of missing…

The problems of hypothesis testing and interval estimation of the squared multiple correlation coefficient of a multivariate normal distribution are considered. It is shown that available one-sided tests are uniformly most powerful, and the one-sided confidence intervals are uniformly most accurate. An exact method of calculating sample size to…

Trust influences interactions among individuals and organizations but has been an elusive concept to define and measure. The Organizational Trust Inventory (OTI) measures three dimensions of organizational trust, as defined by Cummings and Bromiley (in: Kramer and Tyler (eds) Trust in Organizations, 1996), believing or feeling that others: keep…

Teachers and administrators must be able to identify clearly what techniques are effective at improving student learning, which ones are not, and how to develop a set of successful instructional practices based on that knowledge. Research is not typically something that many K-12 teachers think about as part of their regular planning regimen. Many…

When using multiple regression for prediction purposes, the issue of minimum required sample size often needs to be addressed. Using a Monte Carlo simulation, models with varying numbers of independent variables were examined and minimum sample sizes were determined for multiple scenarios at each number of independent variables. The scenarios…