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…

A model-testing approach for evaluating the stability of item response theory item parameter estimates (IPEs) in a pretest-posttest design is illustrated. Nineteen items from the Head Start Measures Battery were used. A moderately high degree of stability in the IPEs for 5,510 children assessed on 2 occasions was found. (TJH)