Recently there has been an increasing level of interest in subtest scores, or subscores, for their potential diagnostic value. Haberman (2008) suggested a method to determine if a subscore has added value over the total score. Researchers have often been interested in the performance of subgroups--for example, those based on gender or…

Providing information to test takers and test score users about the abilities of test takers at different score levels has been a persistent problem in educational and psychological measurement. Scale anchoring, a technique which describes what students at different points on a score scale know and can do, is a tool to provide such information.…

Providing information to test takers and test score users about the abilities of test takers at different score levels has been a persistent problem in educational and psychological measurement (Carroll, 1993). Scale anchoring (Beaton & Allen, 1992), a technique that describes what students at different points on a score scale know and can do,…

Subscores are reported for several operational assessments. Haberman (2008) suggested a method based on classical test theory to determine if the true subscore is predicted better by the corresponding subscore or the total score. Researchers are often interested in learning how different subgroups perform on subtests. Stricker (1993) and…

A simple score test of the normal two-parameter logistic (2PL) model is presented that examines the potential attraction of the normal three-parameter logistic (3PL) model for use with a particular item. Application is made to data from a test from the Praxis™ series. Results from this example raise the question whether the normal 3PL model should…

In item-response theory, if a latent-structure model has an ability variable, then elementary information theory may be employed to provide a criterion for evaluation of the information the test provides concerning ability. This criterion may be considered even in cases in which the latent-structure model is not valid, although interpretation of…

Latent-class item response models with small numbers of latent classes are quite competitive in terms of model fit to corresponding item-response models, at least for one- and two-parameter logistic (1PL and 2PL) models. Provided that care is taken in terms of computational procedures and in terms of use of only limited numbers of latent classes,…