Fallibility in estimating direct effects
Abstract
We use causal graphs and a partly hypothetical example from the Physicians' Health Study to explain why a common standard method for quantifying direct effects (i.e. stratifying on the intermediate variable) may be flawed. Estimating direct effects without bias requires that two assumptions hold, namely the absence of unmeasured confounding for (1) exposure and outcome, and (2) the intermediate variable and outcome. Recommendations include collecting and incorporating potential confounders for the causal effect of the mediator on the outcome, as well as the causal effect of the exposure on the outcome, and clearly stating the additional assumption that there is no unmeasured confounding for the causal effect of the mediator on the outcome.
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SCM weeds out myths and misconceptions from outdated traditions.
“Weeding out myths and misconceptions from outdated traditions (Meek and Glymour, 1994; Greenland et al., 1999; Cole and Hern´ an, 2002; Arah, 2008; Shrier, 2009; Pearl, 2009b).”
From Causal inference in statistics: An overview (2009) · cites this paper as Cole and Hern´ an, 2002
It will not be sufficient to measure the association between gender (X) and hiring (Y) for a given level of qualification Z, because conditioning on the mediator Z may create spurious associations between X and Y even when there is no direct effect of X on Y.
“For example, it will not be sufficient to measure the association between gender ( X ) and hiring ( Y ) for a given level of qualification Z , because, by conditioning on the mediator Z , we may create spurious associations between X and Y even when there is no direct effect of X on Y (Pearl, 1998; Cole and Hern´ an, 2002).”
From Causal inference in statistics: An overview (2009) · cites this paper as Cole and Hernán, 2002
SCM weeds out myths and misconceptions from outdated traditions.
“Weeding out myths and misconceptions from outdated traditions (Meek and Glymour, 1994, Greenland et al., 1999, Cole and Hernan, 2002, Arah, 2008, Shrier, 2009, Pearl, 2009c).”
From An Introduction to Causal Inference (2010) · cites this paper as Cole and Hernan, 2002
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- Authors
- Cole, S. R., & Hernán, M. A.
- Affiliations
- Johns Hopkins University (US)
- Corresponding author
- Cole, Stephen R
- ORCID
- Cole, Stephen R
- Venue
- International Journal of Epidemiology
- Publisher
- Oxford University Press (OUP)
- Published
- 2002-02
- Volume
- 31
- Issue
- 1
- Pages
- 163-165
- ISSN
- 0300-5771 (ISSN-L)
- 1464-3685
- OpenAlex
- W2157524492
- Cited by
- 548
- References
- 5
- Citations by year
- 2026: 8 · 2025: 11 · 2024: 12 · 2023: 13 · 2022: 21 · 2021: 12 · 2020: 12 · 2019: 23 · 2018: 4 · 2017: 24 · 2016: 25 · 2015: 34 · 2014: 48 · 2013: 26 · 2012: 46
- FWCI
- 14.57
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- International Journal of Epidemiology (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institute of Allergy and Infectious Diseases (U01 AI42590, U01AI042590, U01AI035043, U01 AI-35043)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Physical Sciences › Computer Science › Artificial Intelligence › Bayesian Modeling and Causal Inference
- Keywords
- direct effect, mediation analysis, unmeasured confounding, causal graphs, Physicians' Health Study, causal inference
- MeSH terms
- Aspirin, Humans, Myocardial Infarction, Platelet Aggregation Inhibitors, Epidemiologic Research Design, Bias, Causality, Confounding Factors, Epidemiologic, Odds Ratio
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