[Statlist] Statistics Seminar, December 10 2010 at 15h15

[Schaffner Portillo Maroussia]

STATISTICS SEMINAR

Friday, December 10, 2010 - 15h15

Room MA A1 10 - EPFL

Dr. Claire Gormley
University College Dublin

will be speaking on :


Statistical modeling of social network data in the presence of covariates



Abstract:
Social network data represent the interactions between a group of social actors. Interactions between colleagues and friendship networks are typical examples of such data. The latent space model for social network data locates each actor in a network in a latent (social) space and models the probability of an interaction between two actors as a function of their locations. The latent position cluster model extends the latent space model to deal with network data in which clusters of actors exist - actor locations are drawn from a nite mixture model, each component of which represents a cluster of actors. A mixture of experts model builds on the structure of a mixture model by taking account of both observations and associated covariates when modeling a heterogeneous population. Here, a mixture of experts extension of the latent position cluster model is developed. The mixture of experts framework allows covariates to enter the latent position cluster model in a number of ways, yielding different model interpretations. Estimates of the model parameters are derived in a Bayesian framework using a Markov Chain Monte Carlo algorithm. The algorithm is generally computationally expensive - ideas from optimization transfer algorithms are used to derive surrogate proposal distributions which shadow the target distributions, reducing the computational burden. The methodology is demonstrated through an illustrative example detailing relations between a group of lawyers in the USA. Joint work with Brendan Murphy.



Best regards.



Maroussia Schaffner Portillo

EPFL-SB-SMAT

Phone: 37922

 http://smat.epfl.ch/seminar/seminar.php


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