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Measures of association: an overview with examples from Canadian emergency medicine research

Published online by Cambridge University Press:  21 May 2015

Andrew Worster  and
Brian H. Rowe
Andrew Worster*
Affiliation:
Research Division of Emergency Medicine, Hamilton Health Sciences Corporation, and McMaster University, Hamilton, Ont
Brian H. Rowe
Affiliation:
Division of Emergency Medicine and Department of Public Health Sciences, University of Alberta, and Capital Health Authority, Edmonton, Alta
*
Department of Emergency Medicine, Hamilton Health Sciences Corporation, 237 Barton St. E, Hamilton ON L8N 3Z5; 905 521-2100 x73136, fax 905 527-7051, worster@hhsc.ca

Abstract

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The authors of studies often report their results using abbreviated terms such as RR, OR, ARR, RRR and NNT. These terms are quantities that express the strength of association between the dependent and independent variables and are collectively referred to as measures of association. The similarity between these measures and the multiple terms by which each is referred can be confusing. The purpose of this article is to explain in a straightforward manner the purpose, derivation, and limitations of some of the more commonly used categorical measures of association, including relative risk, odds ratio, absolute and relative risk reduction and number needed to treat, using results from recent emergency medicine studies published by Canadian researchers.

Keywords

Evidence-based medicineemergency medicinedecision-makingtherapeutics
Type
Methodology: The Science of EM • Méthodologie: Science de la MU
Information
Canadian Journal of Emergency Medicine , Volume 3 , Issue 3 , July 2001 , pp. 219 - 223
Copyright
Copyright © Canadian Association of Emergency Physicians 2001

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