This guide will help researchers design and implement impact studies in education so that the findings are more generalizable to the study's target population. Guidance is provided on key steps that researchers can take, including defining the target population, selecting a sample of schools--and replacement schools, when needed--managing school…

We conducted a meta-analysis of 13 instructional arrangement studies that were conducted with children with autism spectrum disorders to improve academic and social communication skills and behavior. Results across the studies indicate that peer-mediated instructional arrangement is a robust method for teaching and improving various academic and…

In this paper the authors present a new method for sample selection for scale-up experiments. This method uses propensity score matching methods to create a sample that is similar in composition to a well-defined generalization population. The method they present is flexible and practical in the sense that it identifies units to be targeted for…

The question of generalizability or the usefulness of qualitative research results beyond the confines of the primary site, sample, and study has been hotly debated by qualitative researchers for decades. When examining this question of generalization the first surprising finding is there appears to be no general consensus about the definition,…

Traditionally, research has been seen as a process in which particular cases are studied in order to produce generalisations that can later be applied to other situations. This is arguably the case, for instance, of plain statistical generalisation from samples to populations, but also of grounded theory, local theory and democratic theory. Other…

This issue of "FOCUS" discusses external validity and what rehabilitation researchers can do to help practitioners answer the question "How far can we generalize this finding-- is it applicable to other clients/patients, with different characteristics, in dissimilar settings treated by other clinicians?," which clinicians and…

Donald Campbell's approach to causal inference (D. T. Campbell, 1957; W. R. Shadish, T. D. Cook, & D. T. Campbell, 2002) is widely used in psychology and education, whereas Donald Rubin's causal model (P. W. Holland, 1986; D. B. Rubin, 1974, 2005) is widely used in economics, statistics, medicine, and public health. Campbell's approach focuses on…

This report summarizes the complex research literature on quantitative methods for assessing how impacts of educational interventions on instructional practices and student learning differ across students, educators, and schools. It also provides technical guidance about the use and interpretation of these methods. The research topics addressed…

The developmental course in the distance-speed-time domain is still a matter of debate. Traditional stage models are contested by theories of continuous development and adaptive thinking. In the present work, we introduce a formal framework for modelling the developmental course in this domain, grounding on Competence-based Knowledge Space Theory.…

The most commonly used measures of locus of control are Rotter's Internality-Externality Scale (I-E) and Nowicki and Strickland's Internality-Externality Scale (NSIE). A reliability generalization study is conducted to explore variability in I-E and NSIE score reliability. Studies are coded for aspects of the scales used (number of response…

Meta-analytic reliability generalizations (RGs) are limited by the scarcity of reliability reporting in primary articles, and currently, RG investigators lack a method to quantify the impact of such nonreporting. This article introduces a stepwise procedure to address this challenge. First, the authors introduce a formula that allows researchers…

Calculating and reporting appropriate measures of effect size are becoming standard practice in psychological research. One of the most common scenarios encountered involves the comparison of 2 groups, which includes research designs that are experimental (e.g., random assignment to treatment vs. placebo conditions) and nonexperimental (e.g.,…

We reviewed twelve studies that used the constant time delay (CTD) procedure to teach chained tasks to individuals with developmental disabilities from years 1996-2006. Variables analyzed include types of tasks that have been taught with the procedure, how effective CTD has been in teaching participants, and whether researchers have investigated…

This article presents a cohesive, empirically grounded categorization system differentiating the types of generalizations students constructed when reasoning mathematically. The generalization taxonomy developed out of an empirical study conducted during a 3-week teaching experiment and a series of individual interviews. Qualitative analysis of…

Several researchers have employed milieu therapy to address the communication needs of children with autism spectrum disorder (ASD). Thus, the purpose of this review is to examine milieu therapy, particularly, the environments and individuals involved in the training and the effectiveness of milieu therapy with children who have a diagnosis of ASD…