A general model for two-level multivariate data, with responses possibly missing at random, is described. The model combines regressions on fixed explanatory variables with structured residual covariance matrices. The likelihood function is reduced to a form enabling computational methods for estimating the model to be devised. (Author)

Monte Carlo studies were conducted to compare four multivariate analysis of variance (MANOVA) simultaneous test procedures (STPs) in terms of power and Type I error under various conditions including violations of MANOVA assumptions. Results do not support the hypothesis that the moderately restricted STP is a good compromise between…

Type I error rates for the Johansen test were estimated using simulated data for a variety of conditions. Results indicate that Type I error rates for the Johansen test depend heavily on the number of groups and the ratio of the smallest sample size to the number of dependent variables. Sample size guidelines are presented. (SLD)

Lazraq and Cleroux (Psychometrika, 2002, 411-419) proposed a test for identifying the number of significant components in redundancy analysis. This test, however, is ill-conceived. A major problem is that it regards each redundancy component as if it were a single observed predictor variable, which cannot be justified except for the rare…

The transtheoretical model has been applied to many addictive disorders. In this study, psychometrics properties of the University of Rhode Island Change Assessment (URICA) scale were evaluated in 234 pathological gamblers initiating treatment. Four components were identified--reflective of precontemplation, contemplation, action, and maintenance…

A number of important applications require the clustering of binary data sets. Traditional nonhierarchical cluster analysis techniques, such as the popular K-means algorithm, can often be successfully applied to these data sets. However, the presence of masking variables in a data set can impede the ability of the K-means algorithm to recover the…

To obtain a more complete understanding of personal epistemology this study examines two epistemic paradigms - ways of knowing (specifically connected knowing and separate knowing) and epistemological beliefs (specifically beliefs about knowledge structure, knowledge stability, learning speed, and learning ability). Participants were 107 college…

Group-level parametric and non-parametric item response theory models were applied to the Consumer Assessment of Healthcare Providers and Systems (CAHPS[R]) 2.0 core items in a sample of 35,572 Medicaid recipients nested within 131 health plans. Results indicated that CAHPS responses are dominated by within health plan variation, and only weakly…

The study of confusion data is a well established practice in psychology. Although many types of analytical approaches for confusion data are available, among the most common methods are the extraction of 1 or more subsets of stimuli, the partitioning of the complete stimulus set into distinct groups, and the ordering of the stimulus set. Although…

Basic motor skills development is achieved through the implementation of different types of physical education programs. The purpose of this study was to investigate and to compare the effect of a developmentally appropriate music and movement program and of a developmentally appropriate physical education program on the development of jumping and…

We examined the association between reading and general cognitive ability (g) in a population-based sample of 6,476 pairs of 7-year-old twins. Additive genetic influences largely accounted for individual differences in reading and the covariation between reading and g. Furthermore, both genetic and shared environmental influences on reading and g…

Since data in social and behavioral sciences are often hierarchically organized, special statistical procedures for covariance structure models have been developed to reflect such hierarchical structures. Most of these developments are based on a multivariate normality distribution assumption, which may not be realistic for practical data. It is…

The utility of single-case vs. group studies has been debated in neuropsychology for many years. The purpose of the present study is to illustrate an alternative approach to group studies of aphasia, in which the same symptom dimensions that are commonly used to assign patients to classical taxonomies (fluency, naming, repetition, and…

While it is well known that reading is highly heritable, less has been understood about the bases of these genetic influences. In this paper, we review the research that we have been conducting in recent years to examine genetic and environmental influences on the particular reading processes specified in the "dual-route" cognitive model of…

With the 2004 reauthorization of the Individuals with Disabilities Education Improvement Act (IDEIA), the definition of a specific learning disability was significantly altered. No longer is it required that a student demonstrate a discrepancy between ability and performance to receive educational support (Horowitz, 1999). With this in mind,…