Percentage of uncontaminated correlations (PUC), explained common variance (ECV), and omega hierarchical ([omega]H) have been used to assess the degree to which a scale is essentially unidimensional and to predict structural coefficient bias when a unidimensional measurement model is fit to multidimensional data. The usefulness of these indices…

The purpose of this study was to evaluate the degree of classification quality in the basic latent class model when covariates are either included or are not included in the model. To accomplish this task, Monte Carlo simulations were conducted in which the results of models with and without a covariate were compared. Based on these simulations,…

When conducting item reviews, analysts evaluate an array of statistical and graphical information to assess the fit of a field test (FT) item to an item response theory model. The process can be tedious, particularly when the number of human reviews (HR) to be completed is large. Furthermore, such a process leads to decisions that are susceptible…

The article compares three different methods to estimate effects of task characteristics and to use these estimates for model-based proficiency scaling: prediction of item difficulties from the Rasch model, the linear logistic test model (LLTM), and an LLTM including random item effects (LLTM+e). The methods are applied to empirical data from a…

When using multiple regression for prediction purposes, the issue of minimum required sample size often needs to be addressed. Using a Monte Carlo simulation, models with varying numbers of independent variables were examined and minimum sample sizes were determined for multiple scenarios at each number of independent variables. The scenarios…

Interest in end-of-year accountability exams has increased dramatically since the passing of the No Child Left Behind Act in 2001. With this increased interest comes a desire to use student data collected throughout the year to estimate student proficiency and predict how well they will perform on end-of-year exams. This article uses student…

A procedure for item analysis using distance clustering is described. Items are grouped according to the predominant factors measured, regardless of what they are. The procedure provides an efficient method of treating unanswered items. (Author/RC)

Compares eight models for analyzing count data through simulation in the context of prediction of absenteeism to indicate the extent to which each model produces false positives. Results suggest that ordinary least-squares regression does not produce more false positives than expected by chance. The Tobit and Poisson models do yield too many false…

An optimal unbiased classification rule is proposed based on a longitudinal model for the measurement of change in ability. In general, the rule predicts future level of knowledge by using information about level of knowledge at entrance, its rate of growth, and the amount of within-individual variation. (SLD)