This commentary discusses the issue of small samples in instructed second language acquisition research. We discuss the current state of affairs, and consider the disadvantages of small samples. We also explore other considerations regarding sample size, such as research ethics and ecological validity. We present a range of recommendations for…

Understanding the reason(s) for Differential Item Functioning (DIF) in the context of measurement is difficult. Although identifying potential DIF items is typically a statistical endeavor, understanding the reasons for DIF (and item repair or replacement) might require investigations that can be informed by qualitative work. Such work is…

Visual display of reported impacts is a valuable aid to both reviewers and readers of systematic reviews. Forest plots are routinely prepared to report standardised effect sizes, but where standardised effect sizes are not available for all included studies a forest plot may misrepresent the available evidence. Tabulated data summaries to…

A key issue in quasi-experimental studies and also with many evaluations which required a treatment effects (i.e. a control or experimental group) design is selection bias (Shadish el at 2002). Selection bias refers to the selection of individuals, groups or data for analysis such that proper randomization is not achieved, thereby ensuring that…

Methodological barriers have been highlighted as a primary reason for the limited research with lesbian, gay, and bisexual (LGB) people of color. Thus, strategies for anticipating and addressing potential methodological barriers are needed. To address this need, this article discusses potential challenges associated with conducting research with…

Repeated measures experimental designs, often referred to as "within-subjects" designs, offer researchers opportunities to study research effects while "controlling" for subjects. These designs offer greater statistical power relative to sample size. However, threats to internal validity such as carryover or practice effects…

Views intercoder reliability as a sampling problem for content analyses. Develops a formula for generating sample sizes needed to have valid reliability estimates. Suggests steps for reporting reliability. (TB)

Scale-up is the practice of introducing proven interventions into new settings with the goal of producing similarly positive effects in larger, more diverse populations. Scale-up "research" examines factors that influence the effectiveness of interventions as they are brought to scale across settings. This article has three objectives. First, it…

This article considers various kinds of probability and non-probability samples in both experimental and survey studies. Throughout, how a sample is chosen is stressed. Size alone is not the determining consideration in sample selection. Good samples do not occur by accident; they are the result of a careful design. (Author/JAZ)

This report summarizes the National Job Training Partnership Act (JTPA) Study, which examined the impact of Title IIA of JTPA on participants' employment, earnings, and welfare receipt. Between 1987 and 1989, more than 20,000 adults and out-of-school youths who applied for JTPA services in 16 areas across the country were randomly assigned to a…

The sampling of teachers for nationwide surveys offers a challenging endeavor in obtaining a representative and adequate sample to truly represent opinions of the teachers. Ten national surveys of public school teachers conducted between 1980 and 1985 are presented with respect to their sampling design and procedures. Concepts and theoretical…

Statistical significance is misused in educational and psychological research when it is applied as a method to establish the reliability of research results. Other techniques have been developed which can be correctly utilized to establish the generalizability of findings. Methods that do provide such estimates are known as invariance or…

The nine-volume Survey Kit is designed to help readers prepare and conduct surveys and become better users of survey results. All the books in the series contain instructional objectives, exercises and answers, examples of surveys in use, illustrations of survey questions, guidelines for action, checklists of "dos and don'ts," and…