Proposes a procedure for testing hypotheses regarding the dispersion of responses distributed over taxa that uses the distribution of the number of cells that are empty or are singly occupied. Presents a table showing the number of cases needed to achieve 0.10, 0.05, and 0.01 significance for excessive numbers of empty cells. (SLD)

Many textbooks teach a rule of thumb stating that the mean is right of the median under right skew, and left of the median under left skew. This rule fails with surprising frequency. It can fail in multimodal distributions, or in distributions where one tail is long but the other is heavy. Most commonly, though, the rule fails in discrete…

A special but common type of scenario is one in which a company has a promotion that is designed to make the customer purchase more of their product than they otherwise might. Although this can be aimed specifically at children, it really applies to all persons. The basic premise is that the company issues a "set" of different items or…

The authors describe and illustrate 6 factors that affect the size of a Pearson correlation: (a) the amount of variability in the data, (b) differences in the shapes of the 2 distributions, (c) lack of linearity, (d) the presence of 1 or more "outliers," (e) characteristics of the sample, and (f) measurement error. Also discussed are ways to…

The Western Undergraduate Exchange (WUE) is a regional tuition-reciprocity agreement that enables students from WICHE (Western Interstate Commission for Higher Education) states to enroll in participating two- and four-year public institutions at 150 percent of the enrolling institution's resident tuition. WUE has been operating for more than 20…

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…

In the passionate debates over providing equal educational opportunity for all children, it's frequently argued that large financial inequities create challenges for many public schools, particularly those in lower-income urban areas. This study compares the revenues and operating expenditures of Michigan's urban, suburban, town and rural school…

Given the extent to which our society values education, it is perplexing to learn that we continue to struggle to provide all children, especially homeless children, an adequate education. This troubling issue is the focus of this paper. Specifically, this paper will center around two basic questions; 1) what has the legal system done to ensure…

In this issue's "Classroom Notes" section, the following papers are described: (1) "Sequences of Definite Integrals" by T. Dana-Picard; (2) "Structural Analysis of Pythagorean Monoids" by M.-Q Zhan and J. Tong; (3) "A Random Walk Phenomenon under an Interesting Stopping Rule" by S. Chakraborty; (4) "On Some Confidence Intervals for Estimating the…

Test statistics based on the assumption that test scores are interval rather than ordinal quality data are questioned. New statistical techniques which do not rely on this assumption are presented. (JKS)

This paper provides a brief review of the concepts of confidence intervals, effect sizes, and central and noncentral distributions. The use of confidence intervals around effect sizes is discussed. A demonstration of the Exploratory Software for Confidence Intervals (G. Cuming and S. Finch, 2001; ESCI) is given to illustrate effect size confidence…

While violation of the homogeneity of variance assumption has received considerable attention, violation of the assumption of normally distributed data has not received as much attention. As a result, researchers may have the mistaken impression that as long as the assumptions of independence of observations and homogeneity of variance are…

Two multivariate probability distributions, a generalized beta distribution and a generalized F distribution, are derived. Formulas for the moments of these distributions are given and an example of the bivariate generalized beta is presented. (Author/JKS)

DIMTEST is a nonparametric statistical test procedure for assessing unidimensionality of binary item response data that uses the T-statistic of W. F. Stout (1987). This study investigates the performance of the T-statistic with respect to different shapes of ability distributions and confirms its nonparametric nature. (SLD)

Outlines the multivariate latent distribution specification and the corresponding interpretation issues. Also shows the univariate formulation and some alternative parameterizations that are useful in the estimation phase. Illustrates the procedures through an application to student ratings data. (SLD)