Evidence map›Paper›PMID 29040562›Full record

ArticleInternational journal of epidemiology2018

Collider scope: when selection bias can substantially influence observed associations.

Marcus R Munafò, Kate Tilling, Amy E Taylor, David M Evans, George Davey Smith

Abstract read
In one paragraph

Article in International journal of epidemiology, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 472 papers, 5 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
472citing papers in PubMed, 5 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

472 citing papers in PubMed, 5 syntheses or guidelines pooled it.

  1. Pooled it
  2. Pooled it
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  4. Pooled it
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  7. Trial
  8. Observational
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  16. Review
  17. Association of genetic risk and physical activity with incident type 2 diabetes.The Journal of clinical endocrinology and metabolism · 2026
    Article
  18. Article
  19. Are There Causal Associations Between Obsessive-Compulsive Disorder and Cardiometabolic Phenotypes? A Genetic Correlation and Bi-Directional Mendelian Randomization Study.American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics · 2026
    Article
  20. Loneliness as an Interface Between Alzheimer's Disease and Suicidal Behaviour: A Methodological Concern.Psychogeriatrics : the official journal of the Japanese Psychogeriatric Society · 2026
    Article

412 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Marcus R MunafòMRC Integrative Epidemiology Unit.
Kate TillingMRC Integrative Epidemiology Unit.
Amy E TaylorMRC Integrative Epidemiology Unit.
David M EvansMRC Integrative Epidemiology Unit.
George Davey SmithMRC Integrative Epidemiology Unit.

Funding

Biotechnology and Biological Sciences Research Council BB/I025263/1Biotechnology and Biological Sciences Research Council BBI025751/1British Heart FoundationCancer Research UKMedical Research Council G9815508Medical Research Council MC_PC_15018Medical Research Council MC_QA137853Medical Research Council MC_UU_00011/7Medical Research Council MC_UU_12013/1Medical Research Council MC_UU_12013/2Medical Research Council MC_UU_12013/4Medical Research Council MC_UU_12013/6Medical Research Council MC_UU_12013/8Medical Research Council MC_UU_12013/9Wellcome TrustWellcome Trust 102215/2/13/2
6 · The paper itself

Abstract

Large-scale cross-sectional and cohort studies have transformed our understanding of the genetic and environmental determinants of health outcomes. However, the representativeness of these samples may be limited-either through selection into studies, or by attrition from studies over time. Here we explore the potential impact of this selection bias on results obtained from these studies, from the perspective that this amounts to conditioning on a collider (i.e. a form of collider bias). Whereas it is acknowledged that selection bias will have a strong effect on representativeness and prevalence estimates, it is often assumed that it should not have a strong impact on estimates of associations. We argue that because selection can induce collider bias (which occurs when two variables independently influence a third variable, and that third variable is conditioned upon), selection can lead to substantially biased estimates of associations. In particular, selection related to phenotypes can bias associations with genetic variants associated with those phenotypes. In simulations, we show that even modest influences on selection into, or attrition from, a study can generate biased and potentially misleading estimates of both phenotypic and genotypic associations. Our results highlight the value of knowing which population your study sample is representative of. If the factors influencing selection and attrition are known, they can be adjusted for. For example, having DNA available on most participants in a birth cohort study offers the possibility of investigating the extent to which polygenic scores predict subsequent participation, which in turn would enable sensitivity analyses of the extent to which bias might distort estimates.

Indexed as

Cohort StudiesPatient SelectionCross-Sectional StudiesHumansSelection Bias

Identifiers

PMID29040562
PMCPMC5837306

What OpenQuestion holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.