Can I draw your attention to RSS Manchester meeting on 10th December (next
Wednesday)? Note that the meeting room is now G107, not G209 as previously
arranged.
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10th December, 5pm, Room G.107, Alan Turing Building, University of
Manchester.
RICHARD EMSLEY (University of Manchester)
Mediation and moderation of treatment effects in randomly controlled trials of
complex interventions
Complex intervention trials should be able to answer both pragmatic and
explanatory questions in order to test the theories motivating the
intervention and help understand the underlying nature of the clinical
problem being tested. Key to this is the estimation of direct effects of
treatment and indirect effects acting through intermediate variables, such as
mediators. Using psychological treatment trials as an example of complex
interventions, this talk explains statistical methods which evaluate both
direct and indirect effects in the presence of hidden confounding between
mediator and outcome. We introduce principal stratification and structural
mean models, and discuss approaches for attaining identifiability of key
parameters of the basic causal model. Assuming that there is no direct effect
of treatment leads to the use of instrumental variable methods, using
randomisation and its interactions with baseline covariates as instruments.
The new methodology is illustrated with motivating examples of randomised
trials from the mental health literature.
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Best wishes
John
John Logsdon
Secretary
RSS Manchester Local Group
[log in to unmask]
http://www.rss-manchester.org
0161 445 4951
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