On the collapsibility of measures of effect in the counterfactual causal framework

Anders Huitfeldt, Mats J. Stensrud, Etsuji Suzuki

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1 Citation (Scopus)


The relationship between collapsibility and confounding has been subject to an extensive and ongoing discussion in the methodological literature. We discuss two subtly different definitions of collapsibility, and show that by considering causal effect measures based on counterfactual variables (rather than measures of association based on observed variables) it is possible to separate out the component of non-collapsibility which is due to the mathematical properties of the effect measure, from the components that are due to structural bias such as confounding. We provide new weights such that the causal risk ratio is collapsible over arbitrary baseline covariates. In the absence of confounding, these weights may be used for standardization of the risk ratio.

Original languageEnglish
Article number1
JournalEmerging Themes in Epidemiology
Issue number1
Publication statusPublished - Jan 7 2019


ASJC Scopus subject areas

  • Epidemiology

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