In this paper, the efficiency of conditional maximum likelihood (CML) and marginal maximum likelihood (MML) estimation of the item parameters of the Rasch model in incomplete designs is investigated. The use of the concept of F-information (Eggen, 2000) is generalized to incomplete testing designs. The scaled determinant of the F-information…

Trait psychology implicitly assumes consistency of the personal traits. Mischel, however, argued against the idea of a general consistency of human beings. The present article aims to design a statistical procedure based on an adaptation of the pi* statistic to measure the degree of intraindividual consistency independently of the measure used.…

Biological phenomena can be investigated at multiple levels, from the molecular to the cellular to the organismic to the ecological. In typical biology instruction, these levels have been segregated. Yet, it is by examining the connections between such levels that many phenomena in biology, and complex systems in general, are best explained. We…

The extent to which a scale score generalizes to a latent variable common to all of the scale's indicators is indexed by the scale's general factor saturation. Seven techniques for estimating this parameter--omega[hierarchical] (omega[subscript h])--are compared in a series of simulated data sets. Primary comparisons were based on 160 artificial…

The authors present a Markov Chain Monte Carlo (MCMC) parameter estimation procedure for the generalized graded unfolding model (GGUM) and compare it to the marginal maximum likelihood (MML) approach implemented in the GGUM2000 computer program, using simulated and real personality data. In the simulation study, test length, number of response…

In traditional factor analysis, the variance-covariance matrix or the correlation matrix has often been a form of inputting data. In contrast, in Bayesian factor analysis, the entire data set is typically required to compute the posterior estimates, such as Bayes factor loadings and Bayes unique variances. We propose a simple method for computing…

We give an example of a student project that experimentally explores a topic in random graph theory. We use the "Combinatorica" package in "Mathematica" to estimate the minimum number of edges needed in a random graph to have a 50 percent chance that the graph is connected. We provide the "Mathematica" code and compare it to the known theoretical…

This article describes a simple way to demonstrate powder diffraction in a classroom setting using a dry film of spherical colloids on a glass substrate. Use of transparent, elastomeric poly(dimethylsiloxane) as a supporting substrate for the spheres rather than glass enables demonstration of the reciprocal lattice effect. (Contains 4 figures and…

Purpose: Family caregivers comprise the backbone of long-term-care provision in the United States, yet little is known about how the composition and experience of family caregiving has changed over time. Design and Methods: Data are drawn from the 1989 and 1999 National Long-Term Care Survey and Informal Caregiver Survey to develop nationally…

This paper explores the wide range of mathematics content and processes that arise in the secondary classroom via the use of unusual counting problems. A universal pedagogical goal of mathematics teachers is to convey a sense of unity among seemingly diverse topics within mathematics. Such a goal can be accomplished if we could conduct classroom…

In the IEA PIRLS International Report, a number of indices of reading-related constructs were introduced for the purpose of explaining the variation in reading achievement. These indices, however, raise issues of reliability and validity, due to the way in which they are derived and due to the quality of the data. Targeting these issues, the…

To test the theory of mental calibration for mental addition it was hypothesized that the mean reaction time for problems in homogeneous sets will be faster than for problems in heterogeneous sets and that the reaction time was inversely related to ability and development (grade level) and independent of gender. Three sets of 40 addition problems…

The effects of two training sequences on the development of young children's logical operations and number concepts, including rational counting strategies, were investigated. Forty-five preschool children, aged 3.11 to 4.10, were randomly assigned to two treatment groups and one control group. Subjects in the treatment groups received training…

This set of 13 activities, adapted from "Mathmatters: Developing Computational Skills with Developmental Activity Sequences (by Randall Souviney, Tamara Keyser, and Alan Sarver) was designed to help teachers using the Indigenous Mathematics Project materials (in Papua New Guinea) understand the basic processes involved in computation with…

This study was designed to investigate whether the implementation and integration of the use of the Explorer Calculator into the curriculum influenced students in grades three through six. The sample consisted of approximately 440 students who were assigned to the treatment group or the control group. Achievement scores from the Iowa Test of Basic…