Mixture modeling is a widely applied data analysis technique used to identify unobserved heterogeneity in a population. Despite mixture models' usefulness in practice, one unresolved issue in the application of mixture models is that there is not one commonly accepted statistical indicator for deciding on the number of classes in a study…

Probability is an essential tool for understanding heredity and modern genetics, yet many students have difficulty with this topic due to the abstract and quantitative nature of the subject. To facilitate student learning of probability in genetics, we have developed a set of hands-on, cooperative activities that allow students to determine…

The purpose of this study was to examine students' learning of simple machines, a fifth-grade (ages 10-11) forces and motion unit, and student engagement using a teacher-created Multiplayer Educational Gaming Application. This mixed-method study collected pre-test/post-test results to determine student knowledge about simple machines. A survey…

Sensitivity data is defined as involving two response categories, with responses observed at different levels of some variable. The responses are taken to indicate sensitivity to the variable and may be labeled "positive" or "negative." The countback method offers confidence limits for the 50% point, the level of the variable…

Relationships among goal setting, monetary incentives, two indexes of motivation, and performance were examined in an experimental simulation. Results suggested that goal-setting and monetary incentives were related independently to measures of motivation and performance. Incentives, however, had no impact on whether or not subjects set…

A unified approach to model building is developed from the separate techniques of regression, simulation, and factorial design. The methodology is applied in the context of a suburban school district. (Author/LS)

Two independent replications of a sequence of simulations were conducted to aid in the diagnosis and interpretation of equating differences found between representative (random) and matched (nonrandom) samples for three commonly used conventional observed-score equating procedures and one item-response-theory-based equating procedure. (SLD)

The effect of the conditioning score on the results of differential item functioning (DIF) analysis was examined with simulated data. The study demonstrates that results of DIF that rely on a conditioning score can be quite different depending on the conditioning variable that is selected. (SLD)

The nonparametric Mokken model of test data was compared with parametric models using simulated data through latent class analysis. It is demonstrated that latent class analysis provides a consistent comparison of item response models. (SLD)

The fuzzy perspective in statistical analysis is first illustrated with reference to the "Informational Paradigm" allowing us to deal with different types of uncertainties related to the various informational ingredients (data, model, assumptions). The fuzzy empirical data are then introduced, referring to "J" LR fuzzy variables as observed on "I"…

Meta-analytic structural equation modeling (MA-SEM) is increasingly being used to assess model-fit for variables' interrelations synthesized across studies. MA-SEM researchers have analyzed synthesized correlation matrices using structural equation modeling (SEM) estimation that is designed for covariance matrices. This can produce incorrect…

The authors examined the role of the sample-specific simulations (SSS; A. M. Ruscio & J. Ruscio, 2002; J. Ruscio & A. M. Ruscio, 2004) procedure in detecting low base-rate taxa that might otherwise prove elusive. The procedure preserved key distributional characteristics for moderate to high base-rate taxa, but it performed inadequately for low…

The central messages of this paper are that (a) unequal variances may be more prevalent than typically imagined in educational and policy research, and (b) when considering tests of equal variances one needs to be cautious about what is being referred to as "Levene's test" because Levene's test is actually a family of techniques. Depending on…

Computer simulations under three conditions of polytomous differential item functioning (DIF) compared the ability of three different statistical procedures to detect nonuniform DIF. The procedures were a nominal and an ordinal extension of the Mantel-Haenszel statistic, and logistic discriminant function analysis. Results showed that only the…