Reasons/methods for standardizing discriminant function coefficients are reviewed, and use of the pooled within-groups variance estimate is examined. Use of total or pooled within-groups estimates can be justified only on purely mathematical grounds. Total variance estimates offer a more consistent and parsimonious approach than do pooled…

Applications of the confirmatory factor analysis block-diagonal model to published data on 18 multitrait-multimethod matrices were reviewed to show widespread estimation problems. Possible causes of estimation difficulties were explored using computer simulations. These problems make the block-diagonal approach less useful than has generally been…

A model for the age standardization of test scores is presented, which is fitted to the percentile points of the raw score distribution and assumes a linear trend of each percentile with age. The model's applications in standardizing tests and diagnostic plots produced by a computer program--STANEW--are described. (SLD)

This paper proposes a generalization of Thurstonian probabilistic choice models for analyzing both multiple preference responses and their relationships. The approach is illustrated by modeling data from two multivariate preference experiments. Preliminary data analyses show that the extension can yield an adequate representation of multivariate…

A new procedure is proposed for handling nominal variables in the analysis of variables of mixed measurement levels, and a procedure is developed for handling ordinal variables. Using these procedures, a monotonically convergent algorithm is constructed for the FACTALS method for any mixture of variables. (SLD)

A general model for two-level multivariate data, with responses possibly missing at random, is described. The model combines regressions on fixed explanatory variables with structured residual covariance matrices. The likelihood function is reduced to a form enabling computational methods for estimating the model to be devised. (Author)

How syntax affects sentence prosody is explored. It is demonstrated that the lengthening of phase-final words and pausing afterward reflect a distinctly prosodic representation in which phonological constituents are arranged in a hierarchical nonrecursive structure. A model of prosodic pronunciation is also presented. (SLD)

Discusses a classroom-teaching example provided in this issue. Comments that teachers, using curricular materials and activities, adapt, elaborate on, or invent the context of learning in ways that ensure that students study important central concepts in science and mathematics, and that the understandings students develop are accurate and rich.…

Considers some changes that the use of graphics calculators impose on the assessment of calculus and mathematical modeling at the undergraduate level. Suggests some of the ways in which the assessment of mathematical tasks can be modified as the mechanics of calculation become routine and questions of analysis and interpretation assume greater…

Describes two mathematical models of the periodical publishing process based on a theoretical analysis. Discusses the publishing process for periodical literature, explains the continuous model and the discrete model, presents partial differential equations, and demonstrates the adaptability and the validity of the models. (LRW)

Students in a freshmen calculus course should become fluent in modeling physical phenomena represented by integrals, in particular geometric formulas for volumes and arc length and physical formulas for work. Describes how to train students to became fluent in such modeling and derivation of standard integral formulas. Indicates that these lessons…

Explores some of the issues behind mathematical modeling for technology with reference to undergraduate teaching and professional practice. Discusses theory and practice in mathematical modeling and its place and uses of modeling in engineering. (ASK)

Describes some continuous models for growth of the seaweed Macrocystis pyrifera. Uses observed growth rates over several months to derive first-order differential equations as models for growth rates of individual fronds. The nature of the solutions is analyzed and comparison between these theoretical results and documented characteristics of…

A family of finite mixture distribution models is presented that allows specification of basically different developmental processes in distinct latent subpopulations. These models are introduced within the framework of mixed latent Markov chains with multiple indicators per occasion, and they are illustrated with empirical data on therapeutic…

Discusses whether the tradition of accepting point-symmetric item characteristic curves is justified by uncovering the inconsistent relationship between the difficulties of items and the order of maximum likelihood estimates of ability. In this context, proposes a family of models, called the logistic positive exponent family, that provides…