Estimates of sample size requirements for 2 X 2 tables, derived from three approximate formulae, were evaluated by comparison with exact calculations. Although different, the estimates derived from all three formulae were judged adequate for most practical purposes, with the most accurate results being obtained from Cohen's formula. (Author/JKS)

Analysis of Covariance (ANCOVA) is robust with respect to dual violations of the assumptions of equal regression slopes and normality of distributions provided that group sizes are equal, but displays disruptions of empirical significant levels when unequal regression slopes and unequal group sizes are coupled with nonnormal distributions.…

The G index and its generalizations in the six basic factor analytic designs are discussed. G should be used if there is no mutual direction of all the variables. G should also be used if the scale center is more suitable as a reference point than the mean value. (Author/CTM)

Extensions of the Kruskal-Wallis procedure for a factorial design are examined under various degrees and kinds of nonnullity. It was found that the distributions of these test statistics are a function of effects other than those being tested, except under the completely null situation. Their use is discouraged. (Author/JKS)

A recent paper by Wainer and Thissen has renewed the interest in Gini's mean difference, G, by pointing out its robust characteristics. This note presents distribution-free asymptotic confidence intervals for its population value in the one sample case and for difference in the two sample situations. (Author/JKS)

Based on a simple nonparametric procedure for comparing two proximity matrices (matrices which represent the similarities among a set of objects), a measure of concordance (agreement) is introduced that is appropriate when K independent proximity matrices are available. (Author/JKS)

A new computer subroutine has been developed for calculating the tetrachoric correlation coefficient. Recent advances in computing inverse normal and bivariate normal distributions have been utilized. The procedure is useful for item analysis. (Author/JKS)

The use of A', a nonparametic measure of sensitivity in tests of recognition memory, is discussed. In particular, two formulas for computing A' are considered. (Author/SB)

Stochastic ordering properties are investigated for a broad class of item response theory (IRT) models for which the monotone likelihood ratio does not hold. A taxonomy is given for nonparametric and parametric models for polytomous models based on the hierarchical relationship between the models. (SLD)

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)

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…

Discusses ideas underlying nonparametric regression and the parametric bootstrap with an overview of their application to item response theory and the assessment of local dependence. Illustrates the use of the method in assessing local dependence that varies with examinee trait levels. (SLD)

This research examines changes in decision-making styles as a result of participation in scenario planning. A quasi-experimental pretest-posttest design and several nonparametric tests were used to analyze data gathered from research participants in a technology firm in the Northeastern United States. Results show that participants tend to…

Written by a social worker for social work students, this is a nuts and bolts guide to statistics that presents complex calculations and concepts in clear, easy-to-understand language. It includes numerous examples, data sets, and issues that students will encounter in social work practice. The first section introduces basic concepts and terms to…

The (univariate) isotonic psychometric (ISOP) model (Scheiblechner, 1995) is a nonparametric IRT model for dichotomous and polytomous (rating scale) psychological test data. A weak subject independence axiom W1 postulates that the subjects are ordered in the same way except for ties (i.e., similarly or isotonically) by all items of a psychological…