A method for the estimation of covariance structure models under polynomial constraints (such as quadratic constraints) is presented. Estimation is on maximum likelihood principles, and the test statistics, parameter estimates, and standard errors are based on a statistical theory which takes the constraints into account. (Author/JKS)

It is recommended that the significance test of treatment effects in analysis of covariance be conceptualized, not as an analysis of residuals, but as a comparison of models whose parameters are estimated by the principle of least squares. (Author/LMO)

Presents data model based on text data model (TDM), universal relation model, and nonfirst normal form (NFNF) relations, and discusses applicability to text processing and document retrieval systems. Highlights include database technology applied to information retrieval, NFNF and universal relation, and TDM integration with NFNF universal…

Since computer programs have been available for estimating and testing linear causal models, these models have been used increasingly in the behavioral sciences. This paper discusses the problem that very different causal structures may fit the same set of data equally well. (Author/LMO)

Demonstrating petroleum engineering concepts in undergraduate laboratories often requires expensive and time-consuming experiments. To eliminate these problems, a graphical simulation technique was developed for junior-level laboratories which illustrate vapor-liquid equilibrium and the use of mathematical modeling. A description of this…

The EM algorithm is used to derive maximum likelihood estimates for item parameters of the two-parameter logistic item response curves. The observed information matrix is then used to approximate the covariance matrix of these estimates. Simulated data are used to compare the estimated and actual item parameters. (Author/BW)

A model is proposed in which the quantification of inverse proportionality is developed beyond the initial qualitative relation. Based on a task analysis, the model was tested with 36 eleven-year-old students in a training experiment using a balance task. (MNS)

The binomial error model includes form-to-form difficulty differences as error variance and leads to Ruder-Richardson formula 21 as an estimate of reliability. If the form-to-form component is removed from the estimate of error variance, the binomial model leads to KR 20 as the reliability estimate. (Author/BW)

Presents a formal model for specification of logical requirements of computer-based information systems that incorporates structural and dynamic aspects based on two separate models: the Logical Information Processing Structure and the Logical Information Processing Network. The model's role in systems development is discussed. (MBR)

Several varieties of perceptual independence are investigated, including sampling independence, dimensional orthogonality, stimulus separability and integrality, and performance parity. A general multivariate perceptual theory is developed, and a precise definition of perceptual independence is offered. (Author/LMO)

Six hundred twenty-six subjects from the University of Arizona participated in an investigation designed to examine congruence of a math domain hierarchy validated psychometrically and validated instructionally. Three studies revealed congruence between hierarchies validated psychometrically and instructionally. Generalization and transfer were…

Structural equation modeling procedures were used to verify a causal relationship between the phonological, word recognition, reading rate, and comprehension components of the reading process. Results indicated proficiency in phonological skills was important for development of word recognition ability, a major contributor to reading…

This paper considers the relation of education and of scientific and technical knowledge developed through research and development to labor productivity growth within the medium term. The empirical significance of sources of productivity growth is tested using data for the United States and 14 other nations. (Author/MLF)

Three different models with continuous materials, discontinuous materials, and number lines were used to study the operation concept in six investigations on multiplication with fractions with pupils aged 11-12 in a Penang International School. All approaches could be understood by pupils, but they preferred the area and fractional models. (MNS)

Describes operations research as an important management tool that can aid library managers in effectively using available resources and as a set of analytical tools that can enable researchers to better understand library and information services. Early history, definition, models, applications to libraries, and impact are noted. Twenty-five…