Methods for estimating the mean and variance of latent ability parameters of a normally distributed population that has been tested with Rasch model-calibrated test items are discussed. Methods for checking the normality of the population are also included. (JKS)

Urry's procedure for approximating latent trait test models is shown to tend to underestimate item discriminatory power and overestimate item difficulty. A method for correcting these biases is provided, and implications of the procedures are discussed. (Author/JKS)

Presents a mathematical model for simulating a newspaper financial system. Includes the effects of advertising and circulation for predicting advertising linage as a function of population, income, and advertising rate. (RL)

A problem illustrating how physics and mathematics complement one another when analyzing problems of the physical world is described. (JT)

Examines the concept of PdV work and the harmonic oscillator as an example of a thermodynamic system with properties analogous to an ideal gas. (SL)

A method is described to help identify important groups in an organization, rank their probable actions, and arrive at a list of the most important group-action pairs for that company. Available from: The Institute of Management Sciences, 146 Westminister Street, Providence, Rhode Island 02903.

An introductory mathematics course for liberal arts students was based on mathematical models and applications. The course outline is provided, and evaluation of the course is discussed. (SD)

Presents adaptation of a probabilistic theoretical model previously used in relevance feedback for use in automatic indexing of documents (in the sense of imitating) human indexers. Methods for model application are proposed, independence assumptions used in the model are interpreted, and the probability of a dependence model is discussed.…

Two stage multiple-comparison procedures give an exact solution to problems of power and Type I errors, but require equal sample sizes in the first stage. This paper suggests a method of evaluating the experimentwise Type I error probability when the first stage has unequal sample sizes. (Author/BW)

Examines relationships among the parameters of the Zipf size-frequency distribution as well as its sampling properties. Highlights include its importance in bibliometrics, tables for the sampling distribution of the maximal value of a finite Zipf distribution, and an approximation formula for confidence intervals. (Author/LRW)

Reparameterization is used to find the maximum likelihood estimates of parameters in a multivariate model having some component variable observable only in polychotomous form. Maximum likelihood estimates are found by a Fletcher Powell algorithm. In addition, the partition maximum likelihood method is proposed and illustrated. (Author/GDC)

This exploratory study determined whether a mathematical model of mastery learning provided a good fit for achievement data obtained from student progress in an introductory, college-level astronomy course for nonmajors. Results provide positive but not compelling evidence that the model of mastery learning is correct. (JN)

This three-part article introduces a population dynamics model of an information processing system. The first part describes the general model and defines the terms used, the second describes the functional relationships between components, and the third explores the hypothesized emergence of increasingly complex, hierarchical information systems.…

Modeling the process by which participants are selected into groups, rather than adjusting for preexisting group differences, provides the basis for several new approaches to the analysis of data from nonrandomized studies. Econometric approaches, the propensity scores approach, and the relative assignment variable approach to the modeling of…

Argues that library book circulation is a binomial rather than a Poisson process, and that individual book popularities are continuous beta distributions. Three examples demonstrate the superiority of beta over negative binomial distribution, and it is suggested that a bivariate-binomial process would be helpful in predicting future book…