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)

Concerns development of children's understanding of data and classification. Studies three intact classrooms worked over several sessions to categorize drawings made by children and progressively mathematize their categorization rules. Concludes that by engaging with data characterized by prototypic rather than crisp membership values, students…

Analyzes the mathematics of rotational and translational motion and how one can influence the other in the context of cams and cranks. Describes how the individual components can be brought together to simulate a four-stroke engine and how the engine animates again using the same simple macro. (Author/ASK)

Analyzes whether school-based management (a corporate business emphasis) in Chicago public high schools improved performance between 1989 and 1994. Malmquist productivity index results show very little improvement in productivity (measured in test scores, truancy, and graduation rates). Second-stage regression results are slightly more positive.…

Corrects for potential bias and inconsistency in the estimated coefficient on market competition (among schools) by constructing a system of equations with endogenous expressions of student achievement and market competition. Policy makers seeking to improve student achievement should encourage market competition among schools. (Contains 13…