方法对比

	效应量	What Works Clearinghouse Standards
领域	研究统计学	Education
方法族	Process / pipeline	Process / pipeline
起源年份	1988	2022
提出者	Jacob Cohen	Institute of Education Sciences (IES), U.S. Department of Education
类型	Concept	Standards and procedures for assessing the causal credibility of education studies
开创性文献	Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Lawrence Erlbaum Associates. ISBN: 0-8058-0283-5	What Works Clearinghouse. (2022). What Works Clearinghouse Procedures and Standards Handbook, Version 5.0. Institute of Education Sciences, U.S. Department of Education.
别名	ES, Cohen's d, standardized effect, practical significance	WWC Standards, WWC Evidence Standards, What Works Clearinghouse Review, WWC Study Rating
相关	4	3
摘要	Effect size quantifies the magnitude of a research finding independent of sample size. While a p-value tells you whether a result is statistically significant, an effect size tells you how big the result is. Jacob Cohen formalized effect size measurement in behavioral sciences (1988), establishing standard benchmarks (small = 0.2, medium = 0.5, large = 0.8 for Cohen's d). Effect sizes are essential for meta-analysis, power analysis, and communicating the practical importance of research findings.	The What Works Clearinghouse (WWC) standards are the protocol the U.S. Institute of Education Sciences uses to judge how much confidence an education study's findings deserve as causal evidence. They specify which designs can support causal claims, how to screen for threats such as attrition and confounding, and how to rate each study — Meets Standards Without Reservations, With Reservations, or Does Not Meet Standards — before synthesizing the body of evidence. The standards are a cornerstone of evidence-based education policy in the United States.