A Monte Carlo simulation study was conducted to determine the bootstrap correction formula yielding the most accurate confidence intervals for robust measures of association. Confidence intervals were generated via the percentile, adjusted, BC, and BC(a) bootstrap procedures and applied to the Winsorized, percentage bend, and Pearson correlation…

Differential item functioning (DIF) may be defined as an item that displays different statistical properties for different groups after the groups are matched on an ability measure. For instance, with binary data, DIF exists when there is a difference in the conditional probabilities of a correct response for two manifest groups. This paper…

Bales studied the flow of interaction in groups of various sizes, attempted to describe some of the basic group processes, and found that the initiation rates change so group members become hierarchially arranged according to these rates. This study focuses on the impact of the distribution of positive and negative rewards on the distribution…

Compared strategies for performing multiple comparisons with nonnormal data under various data conditions, including simultaneous violations of the assumptions of normality and variance homogeneity. Monte Carlo study results show the conditions under which different strategies are most appropriate. (SLD)

Studied planned incomplete data designs for the purpose of substantially reducing the amount of data required for multitrait-multimethod models. Simulations studied the effectiveness of Listwise Deletion, Pairwise Deletion, and the expectation maximization (EM) algorithm. Results indicate that EM is generally precise and efficient. (SLD)

Proposed a new asymptotic formula for estimating the sampling variance of a correlation coefficient corrected for unreliability and range restriction. A Monte Carlo simulation study of the new formula results in several positive conclusions about the new approach. (SLD)

Shows that the procedure recommended by D. Lubinski and L. Humphreys (1990) for differentiating between moderated and nonlinear regression models evidences statistical problems characteristic of stepwise procedures. Interprets Monte Carlo results in terms of the researchers' need to differentiate between exploratory and confirmatory aspects of…

Examined the Type I error rate and the power of the Stout T procedure (DIMTEST) (W. Stout, 19987, 1990) and the Holland-Rosenbaum procedure (P. Holland and P. Rosenbaum, 1986) for normal and nonnormal data sets through a Monte Carlo study. Both procedures performed adequately under some conditions, but the Stout T procedure showed adequate power…

Describes available variance component tests and presents three new score tests. One test uses the asymptotic normal distribution of the test statistic as a reference distribution; the others use a Satterthwaite approximation for the null distribution of the test statistic. Evaluates the performance of these tests through Monte Carlo simulation.…

Examined the effects of ignoring multilevel data structures in nonhierarchical covariance modeling using a Monte Carlo simulation. Results suggest that when the magnitudes of intraclass correlations are less than 0.05 and the group size is small, the consequences of ignoring the data dependence within the multilevel data structures seem to be…

The originally proposed multivariate meta-analysis approach for correlation matrices--analyze Pearson correlations, with each study's observed correlations replacing their population counterparts in its conditional-covariance matrix--performs poorly. Two refinements are considered: Analyze Fisher Z-transformed correlations, and substitute better…

A Monte Carlo simulation technique for generating dichotomous item scores is presented that implements (a) a psychometric model with different explicit assumptions than traditional parametric item response theory (IRT) models, and (b) item characteristic curves without restrictive assumptions concerning mathematical form. The four-parameter beta…

Several approaches to reporting subscale scores can be found in the literature. This research explores a multidimensional compensatory dichotomous and polytomous item response theory modeling approach for subscale score proficiency estimation, leading toward a more diagnostic solution. It also develops and explores the recovery of a Markov chain…

This article introduces a bootstrap generalization to the Modified Parallel Analysis (MPA) method of test dimensionality assessment using factor analysis. This methodology, based on the use of Marginal Maximum Likelihood nonlinear factor analysis, provides for the calculation of a test statistic based on a parametric bootstrap using the MPA…

Cluster randomized trials (CRTs) have been widely used in field experiments treating a cluster of individuals as the unit of randomization. This study focused particularly on situations where CRTs are accompanied by a common complication, namely, treatment noncompliance or, more generally, intervention nonadherence. In CRTs, compliance may be…