This paper introduces an empirical strategy to estimate dynamic treatment effects in randomized trials that provide treatment in multiple stages and in which various noncompliance problems arise such as attrition and selective transitions between treatment and control groups. Our approach is applied to the highly influential four year randomized…

Using research to develop a solid educational foundation can accommodate diverse forces confronting educators, initiate systemic change, and help solve the pupil-teacher ratio (PTR)/class-size puzzle. Small K-3 classes are effective and can be efficient if changes are research-based and exploit class-size and PTR differences. (25 references) (MLH)

Reviews Tennessee's Project Student/Teacher Achievement Ratio (STAR) and puts the results in the context of other nonexperimental evidence about class size. Nonexperimental evidence does not support any achievement gains attributable to class-size reduction, and empirical evidence from STAR has design and implementation flaws that cast doubt on…

Reviews research into class size effects from a methodological viewpoint, concentrating on various strengths and weaknesses of randomized controlled trials (RCT) and observational studies. Discusses population definitions, causation, and generally sets out criteria for valid inferences from such studies. Illustrates with new findings from data in…

Educational research, unfortunately, often focuses on finding statistical differences between overall means or averages. Media reports of research routinely present those differences and little else. This paper discusses the importance of considering the spread of the data in addition to the center and how this is relevant to research focused on…