Combines procedures for single-level mediational analysis with multilevel modeling techniques to test mediational effects in clustered data appropriately. Compared, through simulation, the performance of these multilevel mediational models with that of single-level models in clustered data with various real-world characteristics. (SLD)

Compared effect sizes based on simulated groups for the one-parameter and three-parameter logistic item response theory (IRT) models. Data fit the three-parameter model much better, but there were only minimal differences between the effect sizes based on different models. (SLD)

Examined the effects of ignoring multilevel data structures in nonhierarchical covariance modeling using a Monte Carlo simulation. Results suggest that when the magnitudes of intraclass correlations are less than 0.05 and the group size is small, the consequences of ignoring the data dependence within the multilevel data structures seem to be…

Studied sample sizes for confidence intervals on the increase in the squared multiple correlation coefficient using simulation. Discusses predictors and actual coverage probability and provides sample-size guidelines for probability coverage to be near the nominal confidence interval. (SLD)

For the exploratory analysis of a matrix of proximities or (dis)similarities between objects, one often uses cluster analysis (CA) or multidimensional scaling (MDS). Solutions resulting from such analyses are sometimes interpreted using external information on the objects. Usually the procedures of CA, MDS and using external information are…

In last month's column, the authors examined the different kinds of maps that exist in everyday life. In this month's column, they experience, through simulation, the skills that are required of a cartographer. A cartographer is a person who practices the art of making maps. Cartographers' maps were often unique, visual representations of data.…

Previous computer conferencing research has been concerned with the organizational, technical, social, and motivational factors that support and sustain online interaction. This article studies online interaction from a different perspective. Rather than analyze the processes that sustain discourse, the following research examines how and why…

This study aims to shed light on the main characteristics of the French system for redistributing wealth to families through tax revenues and social transfers. For the purposes of this exercise, the authors used the MYRIADE microsimulation model, which covers most of the redistribution system, though it is limited to monetary flows such as family…

How do communities establish shared communication systems? The Common Knowledge view assumes that symbolic conventions develop through the accumulation of common knowledge regarding communication practices among the members of a community. In contrast with this view, it is proposed that coordinated communication emerges a by-product of local…

This paper describes the construction of pedagogical environments in mathematics classes, centred on mathematical modelling and denominated "investigative scenarios", which stimulate students to investigation, to formulation of problems and to political reflection, as well as the sharing of acquired knowledge with other persons in the community.…

This article applies the Breslow-Day test of trend in odds ratio heterogeneity (BD) to the detection of nonuniform DIF. A simulation study was conducted to assess the power and Type I error rate of BD, as well as a combined decision rule (CDR), whereby a decision of the existence of DIF was based on a combination of the decisions made using BD and…

This article presents an interpretation of autoshaping, and positive and negative automaintenance, based on a neural-network model. The model makes no distinction between operant and respondent learning mechanisms, and takes into account knowledge of hippocampal and dopaminergic systems. Four simulations were run, each one using an "A-B-A" design…

When he conducted the Stanford prison experiment, Philip G. Zimbardo wanted to know who would win--good people or an evil situation--when they were brought into direct confrontation. The situation won; humanity lost. Out the window went the moral upbringings of the young men involved in the experiment, as well as their middle-class civility. Power…

Based on previous neuroscientific evidence indicating activation of the mirror neuron system in response to dynamic facial actions, we hypothesized that facial mimicry would occur while subjects viewed dynamic facial expressions. To test this hypothesis, dynamic/static facial expressions of anger/happiness were presented using computer-morphing…

Two unresolved implementation issues with logistic regression (LR) for differential item functioning (DIF) detection include ability purification and effect size use. Purification is suggested to control inaccuracies in DIF detection as a result of DIF items in the ability estimate. Additionally, effect size use may be beneficial in controlling…