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ERIC Number: EJ933694
Record Type: Journal
Publication Date: 2010-Oct
Pages: 9
Abstractor: As Provided
Reference Count: 27
ISSN: ISSN-1531-7714
Yule-Simpson's Paradox in Research
Goltz, Heather Honore; Smith, Matthew Lee
Practical Assessment, Research & Evaluation, v15 n15 Oct 2010
Yule (1903) and Simpson (1951) described a statistical paradox that occurs when data is aggregated. In such situations, aggregated data may reveal a trend that directly contrasts those of sub-groups trends. In fact, the aggregate data trends may even be opposite in direction of sub-group trends. To reveal Yule-Simpson's paradox (YSP)-type occurrences, researchers must simultaneously consider the effect of an intervention at specific levels and on the overall model to ensure datasets are accurately analyzed and research findings are appropriately interpreted. The primary objectives of this manuscript are to: (1) examine the history of YSP; (2) describe necessary and sufficient causes for YSP occurrences; (3) provide examples of YSP in research and explain YSP's relationship to multi-level modeling including Hierarchical Linear Modeling (HLM); and (4) discuss YSP's implications for researchers. (Contains 2 figures and 2 tables.)
Dr. Lawrence M. Rudner. e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: California; Sweden
Identifiers - Assessments and Surveys: SAT (College Admission Test)