This article addresses the importance of obtaining a sample of an adequate size for the purpose of testing hypotheses. The logic underlying the requirement for a minimum sample size for hypothesis testing is discussed, as well as the criteria for determining it. Implications for researchers working with convenient samples of a fixed size are also…

The health status of people with intellectual disability (ID) is poor, yet very little research has been done on their health needs. There are several barriers to performing this research. The aim of our research was to examine the significant barriers encountered in recruiting adults with ID to participate in research. Our project was a…

In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…

This study introduces an order-constrained Bayes inference framework useful for analyzing data containing dichotomous scored item responses, under the assumptions of either the monotone homogeneity model or the double monotonicity model of nonparametric item response theory (NIRT). The framework involves the implementation of Gibbs sampling to…

Data from international comparative studies in education are generally derived from complex, multi-stage sample designs and rotated assessments. Consequently, care must be taken not only in estimating variance components but also in interpreting them. Target population definitions, the nature of the sampling stages and their sampling units, and…

The Organisation for Economic Cooperation and Development's (OECD's) Programme for International Student Assessment (PISA) surveys, which take place every three years, have been designed to collect information about 15-year-old students in participating countries. PISA examines how well students are prepared to meet the challenges of the future,…

The Monitoring the Future study has provided the nation with a window into the important, but largely hidden, problem behaviors of illicit drug use, alcohol use, and tobacco use. It has provided a clearer view of the changing topography of these problems among adolescents and adults, a better understanding of the dynamics of factors that drive…

Purpose: Description of study participants and documentation of the desired diversity in the Prevention Research Centers Healthy Aging Research Network's Workgroup on Promoting Cognitive Health large multisite study designed to examine attitudes about brain health, behaviors associated with its maintenance, and information-receiving preferences…

Monitoring the Future (MTF), now in its 35th year, has become one of the nation's most relied-upon sources of information on changes taking place in licit and illicit psychoactive drug use among American adolescents, college students, young adults, and more recently, middle-aged adults. During the last three and a half decades, the study has…

Earthquake, a natural disaster, is among the fundamental problems of many countries. If people know how to protect themselves from earthquake and arrange their life styles in compliance with this, damage they will suffer will reduce to that extent. In particular, a good training regarding earthquake to be received in primary schools is considered…

This study examined the gender issue in the performance of students admitted through Universities Matriculation Examination (UME) and pre-degree into the Nigerian Universities. Ex-post facto design of descriptive research was adopted for the study. A proforma was used to collect data from a sample of two hundred and fifty students from the…

Concerned about reports of a 15% decline in HIV testing among high-risk youth in an earlier study in Pittsburgh, this study was initiated to explore reasons why young people are not getting tested for HIV, while gathering data on their respective level of risk taking behaviors. A total of 580 surveys were collected from youth aged between 14 and…

The study investigated adaptation to a standard electropalatographic (EPG) practise palate in a group of eight adults (mean age = 24 years). The participants read the phrase "a CVC" over four sampling conditions: prior to inserting the palate, immediately following insertion of the palate, 45 minutes after palate insertion, and 3 hours after…

This paper provides a framework for developing sampling designs in mixed methods research. First, we present sampling schemes that have been associated with quantitative and qualitative research. Second, we discuss sample size considerations and provide sample size recommendations for each of the major research designs for quantitative and…

Purpose: The primary aim of the research reported here is to provide strategic guidance for the development of a national communication strategy to improve sun protection practice amongst young people. Design/methodology/approach: The research adopted an exploratory approach, employing qualitative focus groups to represent three population groups,…