Alan Krueger's reanalyses of Eric Hanushek's school-productivity data show that Hanushek's "money doesn't matter" conclusions (influential in several states' education-finance hearings) have no factual basis. Hanushek excluded Tennessee's student/teacher ratio study (Project STAR). Also, class size is influencing students' success in…

Conclusive research has shown the benefits of small class size (1:15), especially for primary grades. Large-scale projects in Indiana and Tennessee and numerous smaller studies found that youngsters in small classes obtain higher test scores, participate more eagerly, demonstrate improved behavior, and retain these benefits in later schooling…

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…