Accommodations are commonly provided to address language-related barriers students may experience during testing. Research on the validity of scores from accommodated test administrations remains somewhat inconclusive. The current study investigated item response patterns to understand whether accommodations, as used in practice among English…

Changes to state tests impact the ability of State Education Agencies (SEAs) to monitor change in performance over time. The purpose of this study was to evaluate the Standardized Performance Growth Index (PGIz), a proposed statistical model for measuring change in student and school performance, across transitions in tests. The PGIz is a…

In 1992 N. S. Raju and others proposed a general procedure for assessing differential test functioning (DTF) and item bias (differential item functioning or DIF) in tests developed with unidimensional, multidimensional, or polytomous item response theory (IRT) models. The purpose of this paper is to assess the adequacy and validity of their…

The closed-interval signed area (CSA) and closed-interval unsigned area (CUA) statistics were studied by Monte Carlo simulation to detect differential item functioning (DIF) when the reference and focal groups had different parameter distributions. Different behaviors of the CSA and CUA as functions of the parameters are discussed. (SLD)

Simulated data are used to assess the appropriateness of using separate calibration and between-fit approaches to detecting item bias in the Rasch rating scale model. Results indicate that Type I error rates for the null distribution hold even when there are different ability levels for reference and focal groups. (SLD)

This paper describes an item response theory (IRT) based method of differential item functioning (DIF) detection that involves neither separate calibration nor ability grouping. IRT is used to generate residual scores, scores free of the effects of person or group ability and item difficulty. Analysis of variance is then used to test the group…

Responses to previously calibrated items administered in a computerized adaptive testing (CAT) mode may be used to recalibrate the items. This live-data simulation study investigated the possibility, and limitations, of on-line adaptive recalibration of precalibrated items. Responses to items of a Rasch-based paper-and-pencil licensure examination…

Tools used in scaling proficiency scores from the Second International Assessment of Educational Progress (IAEP) are described. The second IAEP study, conducted in 1991, was an international comparative study of the mathematics and science skills of samples of 9- and 13-year-old students from 20 countries. This paper focuses on part of the second…