In low-stakes assessments, some students may not reach the end of the test and leave some items unanswered due to various reasons (e.g., lack of test-taking motivation, poor time management, and test speededness). Not-reached items are often treated as incorrect or not-administered in the scoring process. However, when the proportion of…

Typically a longitudinal growth modeling based on item response theory (IRT) requires repeated measures data from a single group with the same test design. If operational or item exposure problems are present, the same test may not be employed to collect data for longitudinal analyses and tests at multiple time points are constructed with unique…

Methods of estimating the standard error at different ability levels were compared. Overall, it was found that at a given ability level the standard errors calculated using different formulas are not appreciably different. Further, for most situations the traditional method of calculating a standard error probably provides sufficient precision.…