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ERIC Number: EJ1192537
Record Type: Journal
Publication Date: 2018-Oct
Pages: 17
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0141-1926
EISSN: N/A
Princesses Are Bigger than Elephants: Effect Size as a Category Error in Evidence-Based Education
Simpson, Adrian
British Educational Research Journal, v44 n5 p897-913 Oct 2018
Much of the evidential basis for recent policy decisions is grounded in effect size: the standardised mean difference in outcome scores between a study's intervention and comparison groups. This is interpreted as measuring educational influence, importance or effectiveness of the intervention. This article shows this is a category error at two levels. At the individual study level, the intervention plays only a partial role in effect size, so treating effect size as a measure of the intervention is a mistake. At the meta-analytic level, the assumptions needed for a valid comparison of the relative effectiveness of interventions on the basis of relative effect size are absurd. While effect size continues to have a role in research design, as a measure of the "clarity" of a study, policy makers should recognise the lack of a valid role for it in practical decision-making.
Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A