A typology of four notions of confounding in epidemiology

Confounding is a major concern in epidemiology. Despite its significance, the different notions of confounding have not been fully appreciated in the literature, leading to confusion of causal concepts in epidemiology. In this article, we aim to highlight the importance of differentiating between th...

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Main Author: Etsuji Suzuki
Format: Article
Language:English
Published: Japan Epidemiological Association 2017-02-01
Series:Journal of Epidemiology
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S0917504016300752
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author Etsuji Suzuki
author_facet Etsuji Suzuki
author_sort Etsuji Suzuki
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description Confounding is a major concern in epidemiology. Despite its significance, the different notions of confounding have not been fully appreciated in the literature, leading to confusion of causal concepts in epidemiology. In this article, we aim to highlight the importance of differentiating between the subtly different notions of confounding from the perspective of counterfactual reasoning. By using a simple example, we illustrate the significance of considering the distribution of response types to distinguish causation from association, highlighting that confounding depends not only on the population chosen as the target of inference, but also on the notions of confounding in distribution and confounding in measure. This point has been relatively underappreciated, partly because some literature on the concept of confounding has only used the exposed and unexposed groups as the target populations, while it would be helpful to use the total population as the target population. Moreover, to clarify a further distinction between confounding “in expectation” and “realized” confounding, we illustrate the usefulness of examining the distribution of exposure status in the target population. To grasp the explicit distinction between confounding in expectation and realized confounding, we need to understand the mechanism that generates exposure events, not the product of that mechanism. Finally, we graphically illustrate this point, highlighting the usefulness of directed acyclic graphs in examining the presence of confounding in distribution, in the notion of confounding in expectation.
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spelling doaj.art-aa0b4b3b037842638f630385f613300f2022-12-22T01:24:55ZengJapan Epidemiological AssociationJournal of Epidemiology0917-50401349-90922017-02-01272495510.1016/j.je.2016.09.003A typology of four notions of confounding in epidemiologyEtsuji SuzukiConfounding is a major concern in epidemiology. Despite its significance, the different notions of confounding have not been fully appreciated in the literature, leading to confusion of causal concepts in epidemiology. In this article, we aim to highlight the importance of differentiating between the subtly different notions of confounding from the perspective of counterfactual reasoning. By using a simple example, we illustrate the significance of considering the distribution of response types to distinguish causation from association, highlighting that confounding depends not only on the population chosen as the target of inference, but also on the notions of confounding in distribution and confounding in measure. This point has been relatively underappreciated, partly because some literature on the concept of confounding has only used the exposed and unexposed groups as the target populations, while it would be helpful to use the total population as the target population. Moreover, to clarify a further distinction between confounding “in expectation” and “realized” confounding, we illustrate the usefulness of examining the distribution of exposure status in the target population. To grasp the explicit distinction between confounding in expectation and realized confounding, we need to understand the mechanism that generates exposure events, not the product of that mechanism. Finally, we graphically illustrate this point, highlighting the usefulness of directed acyclic graphs in examining the presence of confounding in distribution, in the notion of confounding in expectation.http://www.sciencedirect.com/science/article/pii/S0917504016300752BiasConfoundingCounterfactualDirected acyclic graphsResponse types
spellingShingle Etsuji Suzuki
A typology of four notions of confounding in epidemiology
Journal of Epidemiology
Bias
Confounding
Counterfactual
Directed acyclic graphs
Response types
title A typology of four notions of confounding in epidemiology
title_full A typology of four notions of confounding in epidemiology
title_fullStr A typology of four notions of confounding in epidemiology
title_full_unstemmed A typology of four notions of confounding in epidemiology
title_short A typology of four notions of confounding in epidemiology
title_sort typology of four notions of confounding in epidemiology
topic Bias
Confounding
Counterfactual
Directed acyclic graphs
Response types
url http://www.sciencedirect.com/science/article/pii/S0917504016300752
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