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Incorporating biological information into network inference using structured shrinkage

Presented by: 
Gwenael Leday MRC Biostatistics Unit
Friday 26th August 2016 - 10:40 to 11:00
INI Seminar Room 1
High-throughput biotechnologies such as microarrays provide the opportunity to study theinterplay between molecular entities, which is central to the understanding of disease biology.The statistical description and analysis of this interplay is naturally carried out with Gaussiangraphical models in which nodes represent molecular variables and edges between them representinteractions. Inferring the edge set is, however, a challenging task as the number of parametersto estimate easily is much larger than the sample size. A conventional remedy is to regularize orpenalize the model likelihood. In network models, this is often done locally in the neighbourhoodof each node. However, estimation of the many regularization parameters is often dicult andcan result in large statistical uncertainties. We show how to combine local regularization withglobal shrinkage of the regularization parameters, via empirical Bayes (EB), to borrow strengthbetween nodes and improve inference. Furthermore, we show how one can use EB so the level ofregularization may dier across an arbitrary number of predened groups of interactions. Suchauxiliary information is often available in Biology. It is shown that accurate prior information cangreatly improve the reconstruction of the network, but need not harm the reconstruction if wrong.
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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons