Studied whether circular equating could provide an adequate measure of various types of equating error when applied to different equating methods under different equating designs. Analyses and simluations show that circular equating is generally invalid as a criterion to evaluate the adequacy of equating. (SLD)

Proposed a refinement, based on the stratification of items developed by D. Weiss (1973), of the computerized adaptive testing item selection procedure of H. Chang and Z. Ying (1999). Simulation studies using an item bank from the Graduate Record Examination show the benefits of the new procedure. (SLD)

Discusses challenges in teaching lasers and optical communications to engineers, including the prohibitive cost of laboratory experiments, and describes the development of a computer-based photonics simulation experiment module which provides students with an understanding and visualization of how lasers can be modulated in telecommunications.…

Registered nurses (n=368) participated in a skills recredentialing program in which competencies were assessed by a knowledge test and performance test under simulated conditions and evaluator ratings in actual patient-care situations. No significant differences in results between the simulated and actual conditions support the validity of the…

Extended an Item Response Theory (IRT) method for detection of differential item functioning to the partial credit model and applied the method to simulated data using a stepwise procedure. Then applied the stepwise DIF analysis based on the multiple-group partial credit model to writing trend data from the National Assessment of Educational…

A new generation of e-learning companies is bringing the qualities of live role play to computer simulation. Successful simulations require authentic and relevant scenarios, situations that tap emotions and force actions, unrestricted options, and replayability. (JOW)

Studied the analytic problems associated with a design in which one identifiable group is allocated to each treatment condition and members of these groups are measured to assess the intervention. Results from a simulation study underscore the analytic problems associated with these quasi-experimental or group-randomized designs. (SLD)

When participants use cues to prepare for a likely stimulus or a likely response, reaction times are facilitated by valid cues but prolonged by invalid cues. In studies on combined expectancy effects, two cues give information regarding two dimensions of the forthcoming task. When the two cues consist of two separable stimuli their effects are…

This article illustrates the use of the SAS system for Monte Carlo simulation work in structural equation modeling (SEM). Data generation procedures for both multivariate normal and nonnormal conditions are discussed, and relevant SAS codes for implementing these procedures are presented. A hypothetical example is presented in which Monte Carlo…

This paper reports on studies of the deterministic and stochastic behaviours of a predator-prey system with prey-dependent response function. The first part of the paper deals with the deterministic analysis of uniform boundedness, permanence, stability and bifurcation. In the second part the reproductive and mortality factors of the prey and…

In this activity students will simulate how sedimentary rocks can be changed into metamorphic rocks by intense pressure. The materials needed are two small pieces of white bread, one piece of wheat bread, and one piece of a dark bread (such as pumpernickel or dark rye) per student, two pieces of waxed paper, scissors, a ruler, and heavy books.…

Visual-spatial ability has been identified as one of the primary factors of intelligence. Numerous tests, including paper-and-pencil tasks and laboratory experiments, have attempted to provide an accurate measure of this ability. However, the majority of these tests serve only as surrogate measures of visual-spatial ability and may not provide a…

We use exogenous variation in Social Security payments created by the Social Security benefits notch to estimate how retirees' use of prescription medications responds to changes in their incomes. Using data from the 1993 Wave of the AHEAD, we obtain instrumental variables estimates of the income elasticity of prescription drug use that are…

An experiment, in which students were given the opportunity to perform molecular dynamics simulations on a series of molecular liquids using the Amber suite of programs, is presented. They were introduced to both physical theories underlying classical mechanics simulations and to the atom-atom pair distribution function.

Prior studies of time-to-contact (TTC) focused on judgments of unoccluded approaching objects. P. R. DeLucia, M. K. Kaiser, J. M. Bush, L. E. Meyer, and B. T. Sweet (2003) showed that partial occlusion decreases an object's optical size and expansion rate and that the value of tau derived from the reduced optical size (relative rate of accretion;…