Contingent argument-based approaches to validity require a unique argument for each use, in contrast to more prescriptive approaches that identify the common kinds of validity evidence researchers should consider for every use. In this article, we evaluate our use of an approach that is both prescriptive "and" argument-based to develop a…

The assessment of differential item functioning (DIF) in polytomous items addresses between-group differences in measurement properties at the item level, but typically does not inform which score levels may be involved in the DIF effect. The framework of differential step functioning (DSF) addresses this issue by examining between-group…

When item response data do not satisfy the unidimensionality assumption, multidimensional item response theory (MIRT) should be used to model the item-examinee interaction. This article presents and discusses MIRT analyses designed to give better insight into what individual items are measuring. (SLD)

An ideal process is outlined for test item development and the study of item responses to ensure that tests are sound. Qualitative and quantitative methods are used to assess the item-level validity evidence for high-stakes examinations. A checklist for assessment is provided. (SLD)