This study examined the percentage of task-sampling variability in performance assessment via a meta-analysis. In total, 50 studies containing 130 independent data sets were analyzed. Overall results indicate that the percentage of variance for (a) differential difficulty of task was roughly 12% and (b) examinee's differential performance of the…

This article examines theoretical and empirical issues related to the statistical power of impact estimates for experimental evaluations of education programs. The author considers designs where random assignment is conducted at the school, classroom, or student level, and employs a unified analytic framework using statistical methods from the…

Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to…

The multiple segment factorial vignette design (MSFV) combines elements of experimental designs and probability sampling with the inductive, exploratory approach of qualitative research. MSFVs allow researchers to investigate topics that may be hard to study because of ethical or logistical concerns. Participants are presented with short stories…

This is the first of two reports that summarize the findings from an impact evaluation of a violence prevention intervention for middle schools. This report discusses findings after 1 year of implementation. A forthcoming report will discuss the findings after 2 years and 3 years of implementation. In 2004, the U.S. Department of Education (ED)…

The main goal of the Faculty Perceptions of Intercollegiate Athletics Survey is to examine professors' beliefs about and satisfaction with intercollegiate athletics. The investigation also identifies faculty members' primary concerns about intercollegiate athletics and gathers preliminary data on whether they would join campus-based initiatives…

This article presents a discussion of mixed methods (MM) sampling techniques. MM sampling involves combining well-established qualitative and quantitative techniques in creative ways to answer research questions posed by MM research designs. Several issues germane to MM sampling are presented including the differences between probability and…

One purpose of educational research is to provide information about the likely impact of interventions or treatments on policy-relevant populations of students. Randomized experiments are useful for estimating the causal effects of interventions on the students in schools that participate in the experiments. Unfortunately, the samples of schools…

This study explores a strategy for improving the stability of variance component estimates when only small samples are available, using a series of small, less complex generalizability (G) study designs as a surrogate for a single large design. (Author/BW)

The constraints of conducting evaluations in real-world settings often necessitate the implementation of less than ideal designs. Unfortunately, the standard method for estimating the precision of a result (i.e., confidence intervals [CI]) cannot be used for evaluative conclusions that are derived from multiple indicators, measures, and data…

There is need for objective and reliable single-case research (SCR) results in the movement toward evidence-based interventions (EBI), for inclusion in meta-analyses, and for funding accountability in clinical contexts. Yet SCR deals with data that often do not conform to parametric data assumptions and that yield results of low reliability. A…

The main aim of the study was to evaluate trainee teachers working commitment in their teaching practicum. There were seven component teaching practices and eleven demographic factors. The instrument of the study was extracted from various sources to suit the research design based on Units, Treatments, Observing, and Surveying (UTOS) model…

The purpose of this paper is to point out the importance of sampling considerations and to illustrate the kinds of effect which can be caused by difficulties in sampling by examining three different reports of research. (Author/RK)

Randomization should be employed whenever possible but the use of carefully controlled nonrandomized data to estimate causal effects is a reasonable and necessary procedure in many cases. (Author/BJG)

Generalized symmetric means are redefined in a way which allows them to be calculated for any matrix sampling design. It is proved that these sample generalized symmetric means are unbiased estimates of the analogous population generalized symmetric means. Illustrative examples are given. (Author)