This study investigated the relative model-data fit of an ideal point item response theory (IRT) model (the generalized graded unfolding model [GGUM]) and dominance IRT models (e.g., the two-parameter logistic model [2PLM] and Samejima's graded response model [GRM]) to simulated dichotomous and polytomous data generated from each of these models.…

The mixed Rasch model integrates Rasch and latent class approaches by dividing the population into classes that conform to Rasch models with class-specific parameters, enabling the modeling of qualitatively different patterns of change with the homogeneity assumption retained within, but not between, classes. An empirical example is given. (SLD)

Using one simulated and two real data sets, the effects of the systematic variation of the item-selection procedure and the stepsize method on the operating characteristics of computerized adaptive testing (CAT) for instruments with polychotomously scored rating scale items were studied. The six rating scale CAT procedures used performed well.…

Problems relating to existence of interval scales, dimensionality of a trait, and patterns of item response functions are approached through contrasting scaling methods: item response theory modeling and dual scaling. Similarity of the methods is established through a study of 326 female junior college students in Singapore completing a Likert…

The effectiveness of alternative procedures to correct for rater leniency/stringency effects was studied when true scores were known. Ordinary least squares, weighted least squares, and imputation of the missing data consistently outperformed averaging the observed ratings; and the imputation technique was superior to the least squares methods.…