In a university salary prediction study of 75 faculty members, years of service acted as a negative suppressor variable. The suppressor effect was interpreted as salary compression, or the failure of the organization to recognize seniority with adequate compensation increases while meeting market values for new hires. (SLD)

The importance of regression diagnostics in detecting influential data points is discussed, and five statistics are recommended for the applied researcher. The suggested diagnostics were used on a dataset of 24 subjects, and effects were analyzed. Colinearity-based diagnostics and diagnostics for a variety of procedures are discussed. (SLD)

A theoretical framework for mastery testing based on item response theory and Bayesian decision theory is described and illustrated. Implementation depends on the availability of (1) a computerized test delivery system; (2) a pool of pretested items; and (3) a model relating observed test performance to true mastery status. (SLD)

Mental-rotation task response times from 12 studies involving 505 adults--251 males and 254 females--were used to evaluate 5 hypotheses concerning sex differences derived from an X-linked genetic model. The model assumes that task facilitation in speed of mental rotation is mediated by a recessive gene. Four hypotheses derived from the model were…

Examples of subroutines that generate both symbolic and graphic solutions to differential equations are presented for the two computer algebra systems, MAPLE and Mathematica. Included are the listings for the Mathematica procedures developed for use in this article. (JJK)

The sensitivity of marginal maximum likelihood estimation of item and ability (theta) parameters was examined when prior ability distributions were not matched to underlying ability distributions. Thirty sets of 45-item test data were generated. Conditions affecting the accuracy of estimation are discussed. (SLD)

A Monte Carlo study investigated the use of four cross-validation indices with confirmatory factor analysis models. Influences of sample size, loading size, and degree of model misspecification were studied. Larger sample sizes and better specified models result in better cross-validation results. (SLD)

A crossed random effects model is presented that applies to data with a nested structure to provide maximum likelihood estimates through the EM algorithm. The procedure is illustrated in studies of neighborhood and school effects on educational attainment in Scotland and classroom effects on mathematics learning in the United States. (SLD)

A conceptual framework is provided for thinking about measurement invariance (or bias), and conditions are demonstrated under which invariance can occur. Tools are suggested for addressing such issues as fairness in employment testing, salary equity, and cross-sectional developmental change. Strict factorial invariance is required for…

Inference is considered for the marginal distribution of "X" when ("X", "Y") has a truncated bivariate normal distribution. The "Y" variable is truncated, but only the "X" values are observed. A sample of 87 Otis test scores is shown to be well described by this model. (SLD)

Describes the Chemistry Visualization (ChemViz) Project, a Web venture maintained by the University of Illinois National Center for Supercomputing Applications (NCSA) that enables high school students to use computational chemistry as a technique for understanding abstract concepts. Discusses the evolution of computational chemistry and provides a…

Develops an approach for setting performance targets for schoolchildren, using data-envelopment analysis to identify benchmark pupils who achieve the best observed performance (allowing for contextual factors). These pupils' achievement forms the basis of targets estimated. The procedure also identifies appropriate role models for weaker students'…

Evaluates efficiency of a sample of Spanish secondary schools, focusing on the measurement model's theoretical specification and the "ex post" analysis of results. Highlights characteristics that differentiate the most efficient schools from the least efficient. Stresses the importance of employing information supplied by both…

Features an assignment involving average monthly temperatures that can serve as an example of curve-fitting for a periodic function. (WRM)

Uses a (spatial-econometric) location weighing variable to examine how starting teacher salaries in one Ohio district are influenced by other regional starting salaries. A $1 increase in a neighboring district generates a $.51 to $.96 increase. Size and distance factors help account for spill-over effects. (Contains 34 references.) (MLH)