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SUMMARY:Critically revisiting causal mediation - Vanessa Didelez (Leibniz 
 Institute for Prevention Research and Epidemiology)
DTSTART:20260123T114500Z
DTEND:20260123T123000Z
UID:TALK241846@talks.cam.ac.uk
DESCRIPTION:In this presentation\, I will reflect on why a formal causal t
 reatment of mediation is conceptually and technically demanding\, even tho
 ugh it feels so natural to speak of direct and indirect effects. Standard 
 causal mediation analysis relies on nested counterfactuals and a cross-wor
 ld independence assumption to define and identify natural (in)direct effec
 ts\; their identification in longitudinal or survival settings is essentia
 lly hopeless. An alternative interventionist view (Robins & Richardson\, 2
 011)\, closely aligned in spirit with the decision-theoretic approach of D
 awid (2021)\, leads in the longitudinal/time-to-event case to separable tr
 eatment effects (Didelez\, 2019\; Stensrud et al\, 2022). I will examine w
 hether and how this approach addresses the challenges. Finally\, when assu
 mptions fail\, partial identification through bounds can be considered\; f
 or separable effects\, these bounds are closely related to existing bounds
  for specific natural and path-specific effects (Breum et al\, 2025).\nRef
 erences:Breum\, Didelez\, Gabriel\, Sachs\, (2025). Bounds for causal medi
 ation effects. arXiv preprint arXiv:2512.11549.Dawid (2021). Decision-theo
 retic foundations for statistical causality\, Journal of Causal Inference\
 , 9(1)\, 39-77. https://doi.org/10.1515/jci-2020-0008Didelez (2019). Defin
 ing causal mediation with a longitudinal mediator and a survival outcome\,
  Lifetime Data Analysis 25\, 593-610&nbsp\;Robins JM\, Richardson TS (2011
 ). Alternative graphical causal models and the identification of direct ef
 fects. In: Causality and psychopathology: finding the determinants of diso
 rders and their cures. Oxford University PressStensrud\, Young\, Didelez\,
  Robins\, Hern&aacute\;n (2022). Separable effects for causal inference in
  the presence of competing events\, JASA 117(537)\, 175-183&nbsp\;
LOCATION:Seminar Room 1\, Newton Institute
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