Education lacks scientifically sound studies, whether researchers are examining promotion versus retention, class-size effects, or private voucher schemes. American public schools have educated the world's most productive work force, test scores are rising, and more kids graduate than formerly. Educators should demand compelling evidence before…

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…

This study investigated the possible causes of the contradiction between the results of two projects. Indiana's Prime Time project compared the achievement of students in large (averaging 26 students) and small (averaging 19 students) classrooms in grades 1 through 3. Results indicated that 3 years in smaller classes had little effect on student…