Published in

Oxford University Press (OUP), International Journal of Epidemiology, 2(39), p. 417-420

DOI: 10.1093/ije/dyp334

Links

Tools

Export citation

Search in Google Scholar

Illustrating bias due to conditioning on a collider

Journal article published in 2009 by Stephen R. Cole, Robert W. Platt, Enrique F. Schisterman, Haitao Chu ORCID, Daniel Westreich, David Richardson, Charles Poole
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Upload
Green circle
Postprint: archiving allowed
Upload
Red circle
Published version: archiving forbidden
Policy details
Data provided by SHERPA/RoMEO

Abstract

That conditioning on a common effect of exposure and outcome may cause selection, or collider-stratification, bias is not intuitive. We provide two hypothetical examples to convey concepts underlying bias due to conditioning on a collider. In the first example, fever is a common effect of influenza and consumption of a tainted egg-salad sandwich. In the second example, case-status is a common effect of a genotype and an environmental factor. In both examples, conditioning on the common effect imparts an association between two otherwise independent variables; we call this selection bias.