BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Causal mediation analysis with multiple mediators - Rhian Daniel\,
  LSHTM
DTSTART:20130430T133000Z
DTEND:20130430T143000Z
UID:TALK44516@talks.cam.ac.uk
CONTACT:Dr Jack Bowden
DESCRIPTION:Epidemiologic analyses often attempt to decompose the effect o
 f an exposure on an outcome into its effect via a number of different path
 ways. For example\, the effect of heavy alcohol consumption on systolic bl
 ood pressure (SBP) may be separated into an effect via body mass index (BM
 I)\, an effect via the liver enzyme gamma-glutamyl transpeptidase (GGT)\, 
 an effect via both BMI and GGT\, and an effect via other pathways (not thr
 ough BMI or GGT) - often called the direct effect. Much progress has been 
 made\, mainly due to contributions from the field of causal inference\, in
  understanding the precise nature of estimands that capture these sorts of
  effects\, the assumptions under which they can be identified from data\, 
 and statistical estimation methods for doing so. However\, the focus in th
 e causal inference literature has been mostly on the decomposition of an e
 ffect around and through a single mediator\, or a set of mediators conside
 red en bloc\, hence the two components: a direct and an indirect effect.\n
  \nIn this talk we describe novel\, counterfactually-defined path-specific
  effects that permit the decomposition of the total effect of an exposure 
 on an outcome into a sum of numerous path-specific effects through many me
 diators\, where the mediators are permitted to have a causal effect on eac
 h other. We show that there are many ways in which this decomposition can 
 be done\, discuss the strong structural and modelling assumptions under wh
 ich the effects can be estimated\, together with a sensitivity analysis ap
 proach when a particular subset of the assumptions cannot be justified. Il
 lustrating these ideas using data on alcohol consumption\, SBP\, BMI and G
 GT from the Izhevsk Family Study\, we focus on the ambitious nature of mul
 tiple mediation analyses\, giving some practical guidance on how progress 
 can be made. 
LOCATION:Large  Seminar Room\, 1st Floor\, Institute of Public Health\, Un
 iversity Forvie Site\, Robinson Way\, Cambridge
END:VEVENT
END:VCALENDAR