Unidimensionality and local independence are two common assumptions of item response theory. The former implies that all items measure a common latent trait, while the latter implies that responses are independent, conditional on respondents' location on the latent trait. Yet, few tests are truly unidimensional. Unmodeled dimensions may result in…

Our purpose was to examine different approaches to modeling the time-varying nature of exceptionality classification. Using longitudinal data from one state's mathematics achievement test for 28,829 students in Grades 3 to 8, we describe the reclassification rate within special education and between general and special education, and compare four…

Regression, weighting and related approaches to estimating a population mean from a sample with nonrandom missing data often rely on the assumption that conditional on covariates, observed samples can be treated as random. Standard methods using this assumption generally will fail to yield consistent estimators when covariates are measured with…

In recent years, many states have adopted Item Response Theory (IRT) based vertically scaled tests due to their compelling features in a growth-based accountability context. However, selection of a practical and effective calibration/scaling method and proper understanding of issues with possible multidimensionality in the test data is critical to…

School districts throughout the United States are increasingly providing greater autonomy to local public (non-charter) school principals. In 2005-06, Chicago Public Schools initiated the Autonomous Management and Performance Schools program, granting academic, programmatic, and operational freedoms to select principals. This paper provides…

Many test-based accountability systems, including the No Child Left Behind Act of 2001 (NCLB), place great weight on the numbers of students who score at or above specified proficiency levels in various subjects. Accountability systems based on these metrics often provide incentives for teachers and principals to target children near current…