Illustrating bias due to conditioning on a collider
Open accessAbstract
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.
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Estimation of causal effects using individual level data is most commonly implemented with some version of two-stage least squares (2SLS) estimation.
“Estimation of causal effects using individual level data is most commonly implemented with some version of two-stage least squares (2SLS) estimation (alternative methods include likelihood approaches common in structural equation modelling)54.”
From Mendelian randomization (2022) · cites this paper as [54]
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- Authors
- Cole, S. R., Platt, R. W., Schisterman, E. F., Chu, H., Westreich, D., Richardson, D., & Poole, C.
- Affiliations
- University of North Carolina at Chapel Hill (US)
- McGill University (CA)
- National Institutes of Health (US)
- Corresponding author
- Cole, Stephen R
- Venue
- International Journal of Epidemiology
- Publisher
- Oxford University Press (OUP)
- Published
- 2009-11-19
- Volume
- 39
- Issue
- 2
- Pages
- 417-420
- ISSN
- 0300-5771 (ISSN-L)
- 1464-3685
- PMC
- PMC2846442
- OpenAlex
- W2127992265
- Cited by
- 796
- References
- 21
- Citations by year
- 2026: 49 · 2025: 40 · 2024: 42 · 2023: 56 · 2022: 88 · 2021: 72 · 2020: 79 · 2019: 74 · 2018: 50 · 2017: 48 · 2016: 52 · 2015: 41 · 2014: 42 · 2013: 24 · 2012: 23
- FWCI
- 10.26
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- International Journal of Epidemiology (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Carolina Digital Repository (University of North Carolina at Chapel Hill) (submittedVersion)
- UNC Libraries
- Funders
- National Institutes of Health
- National Institute on Alcohol Abuse and Alcoholism (R01AA01759)
- National Cancer Institute (CA-160-86, P30CA016086)
- National Institute of Allergy and Infectious Diseases (R03AI071763, P30 AI50410, T32AI007001, P30AI050410)
- National Institute of Environmental Health Sciences (P30ES10126), P30ES010126)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Inference
- Keywords
- collider stratification bias, selection bias, confounding
- MeSH terms
- Humans, Regression Analysis, Epidemiologic Research Design, Selection Bias, Odds Ratio, Risk Assessment
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