Standardized testing is ubiquitous in educational assessment, but questions have been raised about the extent to which these test scores accurately reflect students' genuine knowledge and skills. To more rigorously investigate this issue, the current study employed a within-subject experimental design to examine item format effects on primary…

The Early Fractions Test v2.2 is a paper-pencil test designed to measure mathematics achievement of third- and fourth-grade students in the domain of fractions. The purpose, or intended use, of the Early Fractions Test v2.2 is to serve as a measure of student outcomes in a randomized trial designed to estimate the effect of an educational…

This study examined the validity of test accommodation in third-eighth graders using differential item functioning (DIF) and mixture IRT models. Two data sets were used for these analyses. With the first data set (N = 51,591) we examined whether item type (i.e., story, explanation, straightforward) or item features were associated with item…