Illustrating bias due to conditioning on a collider
Open Access
- 19 November 2009
- journal article
- research article
- Published by Oxford University Press (OUP) in International Journal of Epidemiology
- Vol. 39 (2), 417-420
- https://doi.org/10.1093/ije/dyp334
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.Keywords
This publication has 16 references indexed in Scilit:
- Directed Acyclic Graphs, Sufficient Causes, and the Properties of Conditioning on a Common EffectAmerican Journal of Epidemiology, 2007
- The Birth Weight "Paradox" Uncovered?American Journal of Epidemiology, 2006
- A Structural Approach to Selection BiasEpidemiology, 2004
- Quantifying Biases in Causal Models: Classical Confounding vs Collider-Stratification BiasEpidemiology, 2003
- Causal Knowledge as a Prerequisite for Confounding Evaluation: An Application to Birth Defects EpidemiologyAmerican Journal of Epidemiology, 2002
- Data, Design, and Background Knowledge in Etiologic InferenceEpidemiology, 2001
- Confounding in Health ResearchAnnual Review of Public Health, 2001
- Causal Diagrams for Epidemiologic ResearchEpidemiology, 1999
- Causal diagrams for empirical researchBiometrika, 1995
- Design and Analysis of Case-Control StudiesAnnual Review of Public Health, 1982