The Importance of Making Assumptions in Bias Analysis
Open accessAbstract
Quantitative bias analyses allow researchers to adjust for uncontrolled confounding, given specification of certain bias parameters. When researchers are concerned about unknown confounders, plausible values for these bias parameters will be difficult to specify. Ding and VanderWeele developed bounding factor and E-value approaches that require the user to specify only some of the bias parameters. We describe the mathematical meaning of bounding factors and E-values and the plausibility of these methods in an applied context. We encourage researchers to pay particular attention to the assumption made, when using E-values, that the prevalence of the uncontrolled confounder among the exposed is 100% (or, equivalently, the prevalence of the exposure among those without the confounder is 0%). We contrast methods that attempt to bound biases or effects and alternative approaches such as quantitative bias analysis. We provide an example where failure to make this distinction led to erroneous statements. If the primary concern in an analysis is with known but unmeasured potential confounders, then E-values are not needed and may be misleading. In cases where the concern is with unknown confounders, the E-value assumption of an extreme possible prevalence of the confounder limits its practical utility.
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If the actual risk ratio for the effect was 1.4 (the risk ratio of the combined AESI analysis), it could be quite difficult to unambiguously replicate it with observational data given concerns about systematic as well as random errors.
“If the actual risk ratio for the effect was 1.4 (the risk ratio of the combined AESI analysis), it could be quite difficult to unambiguously replicate it with observational data given concerns about systematic as well as random errors. [33-35].”
From Serious adverse events of special interest following mRNA COVID-19 vaccination in randomized trials in adults (2022) · cites this paper as [34]
The Introduction (page not available) identifies uncontrolled confounding as a central concern in observational studies, and Methods > Bounding Factors vs Probabilistic Bias Analysis incorporates random error into an example estimate. These passages support the general concern about systematic and random error, but the paper does not assess whether a true risk ratio of 1.4 could be unambiguously replicated in observational data. (LLM, conf=0.78)
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Self-citation
- Authors
- MacLehose, R. F., Ahern, T. P., Lash, T. L., Poole, C., & Greenland, S.
- Affiliations
- University of Minnesota (US)
- University of Vermont (US)
- Emory University (US)
- University of North Carolina at Chapel Hill (US)
- University of California, Los Angeles (US)
- Corresponding author
- MacLehose, Richard F.
- Venue
- Epidemiology
- Published
- 2021-06-24
- Volume
- 32
- Issue
- 5
- Pages
- 617-624
- ISSN
- 1044-3983 (ISSN-L)
- PMC
- PMC8318561
- OpenAlex
- W3181011780
- Cited by
- 39
- References
- 36
- Citations by year
- 2026: 4 · 2025: 4 · 2024: 10 · 2023: 10 · 2022: 7 · 2021: 4
- FWCI
- 5.78
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Epidemiology (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- Carolina Digital Repository (University of North Carolina at Chapel Hill) (submittedVersion)
- UNC Libraries
- Funders
- National Institute on Aging (R01AG056479)
- National Institute of General Medical Sciences (P20GM103644)
- U.S. National Library of Medicine (R01LM013049)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Keywords
- E-value, unmeasured confounding, bias assessment, bias bounds
- MeSH terms
- Humans, Bias, Confounding Factors, Epidemiologic
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