In the literature of mean and covariance structure analysis, noncentral chi-square distribution is commonly used to describe the behavior of the likelihood ratio (LR) statistic under alternative hypothesis. Due to the inaccessibility of the rather technical literature for the distribution of the LR statistic, it is widely believed that the…

"Peer-Assisted Learning Strategies" is a peer-tutoring program for use in elementary school classrooms to improve student proficiency in reading. Its purpose is to supplement students' existing reading curriculum. "Peer-Assisted Learning Strategies" was developed for use with students with diverse academic needs and has been…

We are grateful to the commentators for providing many stimulating and valuable observations. The main point of our article was to call attention to the overestimation of individual differences correlations in a subset of neuroimaging papers. To structure our discussion of these comments, we list the main points from our paper, note where…

Since 2003, the National Center for Education Statistics (NCES) has compared each state's standard for proficient performance in reading and mathematics by placing the state standards onto the NAEP scale. The procedure, "mapping," allows the level of achievement required for proficient performance in one state to be compared with the…

The purpose of this paper is to provide a typology of sampling designs for qualitative researchers. We introduce the following sampling strategies: (a) parallel sampling designs, which represent a body of sampling strategies that facilitate credible comparisons of two or more different subgroups that are extracted from the same levels of study;…

Almost all introductory and intermediate level statistics textbooks include the topic of confidence interval for the population mean. Almost all these texts introduce the median as a robust measure of central tendency. Only a few of these books, however, cover inference on the population median and in particular confidence interval for the median.…

Monte Carlo methods were used to examine techniques for constructing confidence intervals around multivariate effect sizes. Using interval inversion and bootstrapping methods, confidence intervals were constructed around the standard estimate of Mahalanobis distance (D[superscript 2]), two bias-adjusted estimates of D[superscript 2], and Huberty's…

Three issues need to be decided in the design stage of a longitudinal intervention study: the number of persons, the number of repeated measurements per person, and the duration of the study. The degree to which polynomial effects vary across persons and the drop-out pattern also influence the statistical power to detect intervention effects. This…

Measurement invariance in the partial credit model (PCM) can be conceptualized in several different but compatible ways. In this article the authors distinguish between three forms of measurement invariance in the PCM: step invariance, item invariance, and threshold invariance. Approaches for modeling these three forms of invariance are proposed,…

The purpose of this dissertation study was to determine if a relationship existed between problem-based learning (PBL) content acquisition and academic achievement on teacher-made tests in Career and Technical Education (CTE) courses at the middle school level. The study sample consisted of 20 seventh-grade students enrolled in a CTE keyboarding…

Summer reading setback is a phenomenon that occurs over the summer break when students lose the skills they gained over the school year. While school-year gains are similar for disadvantaged and more-advantaged students, the achievement gap widens over the summer months. Lack of print access and less time spent reading result in greater summer…

The project reported here is conducting repeated randomized control trials of an approach to high school geometry that utilizes Dynamic Geometry (DG) software to supplement ordinary instructional practices. It compares effects of that intervention with standard instruction that does not make use of computer drawing/exploration tools. The basic…

Issues of equity and fairness across subgroups of the population (e.g., gender or ethnicity) must be seriously considered in any standardized testing program. For this reason, many testing programs require some means for assessing test characteristics, such as reliability, for subgroups of the population. However, often only small sample sizes are…

This study was conducted to develop an inventory that measures students' motivation to engage in critical reasoning in online discussions. Inventory items were developed based on theoretical frameworks and then tested on 168 participants. Using exploratory factor analysis, test-retest reliability, and internal consistency, twenty-two items were…

Perceived discrimination has been studied with regard to its impact on several types of health effects. This meta-analysis provides a comprehensive account of the relationships between multiple forms of perceived discrimination and both mental and physical health outcomes. In addition, this meta-analysis examines potential mechanisms by which…