Dear Colleagues,
The Biostatistics Group, part of the Health Sciences Research Group at The University of Manchester, would like to draw your attention to the following seminar:
"Bias formulas for sensitivity analysis for direct and indirect effects"
Prof Dr Tyler VanderWeele
Associate Professor of Epidemiology
Department of Biostatistics, Harvard School of Public Health
Abstract:
A key question in many studies is how to divide the total effect of an exposure into a component that acts directly on the outcome and a component that acts indirectly, i.e. through some intermediate. For example, one might be interested in the extent to which the effect of diet on blood pressure is mediated through sodium intake and the extent to which it is through other pathways. In the context of such mediation analysis, even if the effect of the exposure on the outcome is unconfounded, if control is not made for confounders of the mediator-outcome relationship, then estimates of direct and indirect effects will be biased. Often data is not collected on such mediator-outcome confounding variables; the results in this paper allow researchers to assess the sensitivity of their estimates of direct and indirect effects to the biases from such confounding. Specifically, formulas are provided for the bias in estimates of direct and indirect effects due to confounding of the exposure-mediator relationship and of the mediator-outcome relationship. Under some simplifying assumptions, the formulas are particularly easy to use in sensitivity analysis. The bias formulas are illustrated using examples in the literature concerning direct and indirect effects in which mediator-outcome confounding may be present.
Date: Thursday 10th June 2010
Time: 3.00pm - 4.30pm (refreshments from 3.00pm)
Location:
G306B, Jean MacFarlane Building,
University Place,
The University of Manchester,
Oxford Road,
Manchester,
M13 9PL
Directions and maps:
<http://www.manchester.ac.uk/visitors/travel/directions/>
There is no charge for this seminar and registration is not required. All are welcome to attend!
-----------------
Dr Richard Emsley
MRC Research Fellow,
Biostatistics, Health Sciences Research Group,
School of Community Based Medicine,
1.306 Jean McFarlane Building,
University of Manchester,
Oxford Road,
Manchester. M13 9PL.
Tel: 0161 275 5664
Chairman, Royal Statistical Society Manchester Local Group
http://www.medicine.manchester.ac.uk/staff/RichardEmsley
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