Test-based accountability as well as value-added asessments and much experimental and quasi-experimental research in education rely on achievement tests to measure student skills and knowledge. Yet, we know little regarding fundamental properties of these tests, an important example being the extent of measurement error and its implications for…

Observational methods are increasingly being used in classrooms to evaluate the quality of teaching. Operational procedures for observing teachers are somewhat arbitrary in existing measures and vary across different instruments. To study the effect of different observation procedures on score reliability and validity, we conducted an experimental…

In this technical report, we describe the results of a study of mathematics items written to align with the Common Core State Standards (CCSS) in grades 6-8. In each grade, CCSS items were organized into forms, and the reliability of these forms was evaluated along with an experimental form including items aligned with the National Council of…