Demonstrated that the extra-factor phenomenon (the two-dimensional solution produced when linear factor analysis is applied to a set of unfoldable items) arises because the metric unidimensional unfolding model is equivalent to the unidimensional quadratic factor model and the unidimensional quadratic factor model is not distinguishable from the…

Generalized bilinear models are presented for the statistical analysis of two-way arrays. These models combine bilinear models and generalized linear modeling, and yield a family that includes many useful models. A three-step procedure is presented for analyzing data sets by generalized bilinear models. (SLD)

Used simulation to study two different approaches to latent variable interaction modeling with continuous observed variables: (1) a LISREL 8.30 program and (2) data analysis through PRELIS2 and SIMPLIS programs. Results show that parameter estimation was similar but standard errors were different. Discusses differences in ease of implementation.…

Uses examples of hierarchical linear modeling (HLM) at local and national levels to illustrate proper applications of HLM and dummy variable regression. Raises cautions about the circumstances under which hierarchical data do not need HLM. (SLD)

Describes methods for fitting a fuzzy consensus partition to a set of partitions of the same set of objects. Describes and illustrates three models defining median partitions and compares these methods to an alternative approach to obtaining a consensus fuzzy partition. Discusses interesting differences in the results. (SLD)

There is a growing consensus that developmental dyslexia is associated with a phonological-core deficit. One symptom of this phonological deficit is a subtle speech-perception deficit. The auditory basis of this deficit is still hotly debated. If people with dyslexia, however, do not have an auditory deficit and perceive the underlying acoustic…

A mathematical model of working-memory capacity limits is proposed on the key assumption of mutual interference between items in working memory. Interference is assumed to arise from overwriting of features shared by these items. The model was fit to time-accuracy data of memory-updating tasks from four experiments using nonlinear mixed effect…

A new mathematical tool, known as Engage, Explore, Explain (EEE) model, was developed that was simple for teachers to use, could guide them as they planned exploratory experiences, and was useful to teach mathematics for understanding. The EEE model provides a lesson structure for teachers to use with almost any mathematics topic and can easily be…

The ultimate goal of physics education research (PER) is to develop a theoretical framework to understand and improve the learning process. In this journey of discovery, assessment serves as our headlamp and alpenstock. It sometimes detects signals in student mental structures, and sometimes presents the difference between expert understanding and…

In the United States, 21% of all energy is used in residential buildings (40% of which is for heating and cooling homes). Promising improvements in residential building energy efficiency are underway such as the Building America Program and the Passive House Concept. The ability of improving energy efficiency in buildings is enhanced by building…

The author explored whether 3 workplace conditions were related to teacher mobility decisions. The modeling strategy incorporated a series of binomial and multinomial logistic models to estimate the effects of administrative support, classroom control, and behavioral climate on teachers' decisions to quit teaching or switch schools. The results…

The study of errors made in subtraction is a research subject approached from different theoretical premises that affect different components of the algorithmic process as triggers of their generation. In the following research an attempt has been made to investigate the typology and nature of errors which occur in subtractions and their evolution…

In this article, the author focuses on possible ways to develop the concepts of joint variation and function through the upper primary and lower secondary years of education. The examples demonstrate the building of a range of important mathematical ideas by modelling life-related situations using students' informal and intuitive knowledge. Over…

The never-ending organizational challenge is to allocate available resources to best achieve its goals. Out of this fundamental question several models have evolved. One is a conceptual model--a way to think about how organizations operate. A second is a statistical model estimating the magnitude of relationships among goals and elements of the…

This article describes the use of digital images of real-life phenomena and interactive software to carry out mathematics investigations. (Contains 13 figures.)