A properly chosen test model defines the kind of dependence of the observable behavior on underlying abilities of the persons tested in the form of a data-adequate theory. The limitations and potential of several test models are detailed; and they are critically compared as an aspect of empirical evaluation. (Author/MV)

Statements made in a previous article of this journal concerning the Rasch latent trait test model are questioned. Methods of estimation, necessary sample sizes, several formuli, and the general usefulness of the Rasch model are discussed. (JKS)

Using the assumption of randomly parallel tests and concepts from generalizability theory, three signal/noise ratios for domain-referenced tests are developed, discussed, and compared. The three ratios have the same noise but different signals depending upon the kind of decision to be made as a result of measurement. (Author/JKS)

The principles of modern genetics are extended to study the extinction probabilities of such genetic diseases as sickle-cell anemia, Tay-Sachs disease, and cystic fibrosis. (JT)

A manipulative model for the addition, subtraction, and multiplication of integers is described in which a carpet square with a hole in it and the plug that fits in the hole are "opposites" of each other. Several other models for integer multiplication are briefly described. (MN)

Described is the development of a simulation, or model of an existing congested pedestrian crossing situation by elementary school students in order to conduct trials of their solutions. (MN)

Applies the Box-Jenkins time series methodology to enrollment data for the Virginia community college system. Describes the enrollment data set, the Box-Jenkins approach, and the forecasting results. Discusses the value of one-quarter ahead enrollment forecasts and implications for practice. Provides a technical discussion of the model. (DMM)

Partial knowledge was assessed in a multiple choice vocabulary test. Test reliability and concurrent validity were compared using Rasch-based dichotomous and polychotomous scoring models. Results supported the polychtomous scoring model, and moderately supported J. O'Connor's theory of vocabulary acquisition. (Author/GDC)

The rule space model permits measurement of cognitive skill acquisition and error diagnosis. Further discussion introduces Bayesian hypothesis testing and bug distribution. An illustration involves an artificial intelligence approach to testing fractions and arithmetic. (Author/GDC)

There are many problems that can be translated into the language of graph theory. Such a problem, discussed in this article is to show that in any group of two or more people, there are at least two people who have the same number of acquaintances in the group. (PK)

This special issues describes multidimensional scaling (MDS), with emphasis on proximity and preference models. An introduction and six papers review statistical developments in MDS study design and scrutinize MDS research in four areas of application (consumer, social, cognitive, and vocational psychology). (SLD)

There are two basic approaches offered in current computerized transportation routing and scheduling programs: the mathematical programming approach and the intuitive optimization approach. Lists questions that an informed buyer should ask of the routing and scheduling company. (MLF)

The present study points out problems in the model, indices of familiality, and design used by Benbow, Zonderman, and Stanley in a study of precocious children and their parents. (Author/LMO)

Based on reanalyses of correlational data obtained from the University of Southern California Aptitudes Research Project, this investigation examined the extent to which two higher order factors of semantic content and symbolic content form Guilford's structure-of-intellect model reflected distinct constructs. (Author/LMO)

This study examines a score-difference model for the detection of cheating based on the difference between two scores for an examinee: one based on the appropriate scoring key and another based on an alternative, inappropriate key. It argues that the score-difference method could falsely accuse students as cheaters. (Author/JAZ)