A model-based modification of the standardization index based on a multidimensional item response theory bias modeling approach is presented that detects and estimates differential item functioning (DIF) (item bias) simultaneously for several items as well as differential test functioning (DTF). This SIBTEST procedure is tested through a computer…

Uses chaos theory to investigate the nonlinear phenomenon of population growth fluctuation. Illustrates the use of computers and computer programs to make calculations in a nonlinear difference equation system. (MDH)

Quantitative growth curve models for estimating individual developmental functions from various types of longitudinal data are discussed in the context of investigator assumptions and research design characteristics. Linear and nonlinear models that estimate growth curves are illustrated, and contrasted when they are fit to speech development…

A new test construction model based on the Rasch model is proposed. This model, the cluster-based method, considers groups of interchangeable items rather than individual items and uses integer programing. Results for six test construction problems indicate that the method produces accurate results in small amounts of time. (SLD)

Ignorance of the characteristics of a mixed population may lead to bias in a summary measure of a phenomenon. A test based on sample kurtosis is demonstrated by a simulation study to be more powerful than six other known tests in detecting a class of mixed normal distributions. (SLD)

The feasibility of modeling performance on a three-dimensional rotation task within the context of item response theory was examined using 160 high school students. Eighty pairs of three-dimensional Shepard-Metzler figures were used. This approach to psychometric modeling, incorporating research results from cognitive science, appears workable.…

Combining Rasch and latent class models is presented as a way to overcome deficiencies and retain the positive features of both. An estimation algorithm is outlined, providing conditional maximum likelihood estimates of item parameters for each class. The model is illustrated with simulated data and real data (n=869 adults). (SLD)

Discusses query formulation in information retrieval systems within the framework of adaptive linear models. User preference is emphasized, acceptable ranking strategies are described, query formulation and inductive learning are discussed, relevance feedback and probabilistic approaches are examined, and problems encountered in the design of an…

This study examined the application of the marginal maximum likelihood-EM algorithm to the parameter estimation problems of the normal ogive and logistic polytomous response models for Likert-type items. A rating scale model, based on F. Samejima's (1969) graded response model, was developed. (TJH)

A Bernoulli process model of human immunodeficiency virus (HIV) is used to evaluate infection risks associated with various sexual behaviors (condom use, abstinence, or monogamy). Results suggest that infection is best mitigated through measures that decrease infectivity, such as condom use. (SLD)

Two issues in analysis of interactions in complex linear models are considered. One is the omnibus test for interaction, and the other concerns follow-up tests when the omnibus test is significant. Reconsidered omnibus and follow-up tests are illustrated on an educational data set analyzed using the Statistical Analysis System. (SLD)

Examines the scope and nature of upper elementary school pupils' difficulties with modeling and solving nonroutine additive word problems. Concludes that many errors result from the superficial, stereotyped approach of adding or subtracting two given numbers without considering the appropriateness of that action in relation to the problem context.…

Describes a physics laboratory exercise that focuses on an idea common to all scientific disciplines; that is, there are scaling laws that relate one measurable physical variable to another. (WRM)

Provides a number of basic mathematical models of enrollment trends at a college or university. Seeks to model the effects of retention and recruitment. Utilizes Mathematica in this activity, which introduces students to the notion of modeling something relevant to their campus. (ASK)

Describes an experiment that extends Newton's instantaneous-impulse method of orbital analysis to a graphical method of orbit determination. Discusses the experiment's usefulness for teaching both horizontal projectile motion and instantaneous impulse. (WRM)