Despite the widespread popularity of growth curve analysis, few studies have investigated robust growth curve models. In this article, the "t" distribution is applied to model heavy-tailed data and contaminated normal data with outliers for growth curve analysis. The derived robust growth curve models are estimated through Bayesian…

Statistics, econometrics, investment analysis, and data analysis classes often review the calculation of several types of averages, including the arithmetic mean, geometric mean, harmonic mean, and various weighted averages. This note shows how each of these can be computed using a basic regression framework. By recognizing when a regression model…

This paper uses an approximate average percent-correct methodology to compare the ranks that would be obtained for PISA 2006 countries if the rankings had been derived from items judged by each country to be of highest priority for inclusion. The results reported show a remarkable consistency in the country rank orderings across different sets of…

Most thermodynamic properties are either extensive (e.g., volume, energy, entropy, amount, etc.) or intensive (e.g., temperature, pressure, chemical potential, mole fraction, etc.). By the same token most of the mathematical relationships in thermodynamics can be written in extensive or intensive form. The basic laws of thermodynamics are usually…

The issues related to environmental sustainability can be overwhelming. It is difficult to imagine that actions of one person could make a difference. This article addresses that perception and illustrates the impact of one person, a family and consumer sciences educator, on the lives of others and on environmental resources. Making a difference…

The past two decades of attention to introductory physics education has emphasized enhanced development of conceptual understanding to accompany calculational ability. Given this, it is surprising that current texts continue to rely on the Bohr model to develop a flawed intuition, and introduce correct atomic physics on an ad hoc basis. For…

When grocery stores sell solutions of ammonia, they are labeled "ammonia"; however, when the same solution is purchased from chemical supply stores, they are labeled "ammonium hydroxide". The goal of this experiment is for students to determine which name is more appropriate. In this experiment, students use several different experimental methods…

An introduction to the chemistry of the triazine compound, melamine, is presented as well as a brief discussion of the health impacts on humans and pets when melamine contaminates milk products and pet food. Melamine has repeatedly been in the news, and its topical nature provides an excellent springboard for applications of a variety of chemical…

A simple technique appropriate for introductory materials science courses is outlined for the calculation of bond energies in metals from lattice energies. The approach is applied to body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal-closest-packed (hcp) metals. The strength of these bonds is tabulated for a variety metals and is…

Responds to comments by H. Takooshian and J. K. Tebes on the current author's original article, "Many forms of culture". The current author argued that psychologists tend to focus on too narrow a set of cultures (ethnic and national cultures) and some dimensions of those cultures (individualism-collectivism, independence-interdependence). He then…

Many familiar household objects (such as sausages) involve the maximization of a volume under geometric constraints. A flexible but inextensible membrane bounds a volume which is to be filled to capacity. In the case of the sausage, a full analytic solution is here provided. Other related but more difficult problems seem to demand approximate…

This study investigated the sensitivity of fit indices to model misspecification in within-individual covariance structure, between-individual covariance structure, and marginal mean structure in growth curve models. Five commonly used fit indices were examined, including the likelihood ratio test statistic, root mean square error of…

The fitting of dynamical systems to psychological data offers the promise of addressing new and innovative questions about how people change over time. One method of fitting dynamical systems is to estimate the derivatives of a time series and then examine the relationships between derivatives using a differential equation model. One common…

Differential equations (DEs) are important in mathematics as well as in science and the social sciences. Thus, the study of DEs has been included in various courses in different departments in higher education. The importance of DEs has attracted the attention of many researchers who have generally focussed on the content and instruction of DEs.…

The Jarzynski theorem is perhaps the most recently discovered simple general formula in elementary statistical physics. In this paper, written with a pedagogical aim, we illustrate the physical concepts under the Jarzynski and related results by a detailed calculation with a representative example. The physics of the model is sufficiently…