Item response theory (IRT) methods are generally used to create score scales for large-scale tests. Research has shown that IRT scales are stable across groups and over time. Most studies have focused on items that are dichotomously scored. Now Rasch and other IRT models are used to create scales for tests that include polytomously scored items.…

Although testing accommodations are commonly provided to students with disabilities within large-scale testing programs, research findings on how well accommodations allow for comparable measurement of student knowledge and skill remain inconclusive. The purpose of this study was to examine the extent to which 1 commonly held belief about testing…

The usefulness of latent class modeling in addressing several measurement issues is demonstrated via a study of 74 good and 74 poor readers in grades 5 and 6. Procedures were particularly useful for assessing the hierarchical relation among skills and for exploring issues related to item domains. (SLD)