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College of Arts & Sciences
Department of Statistics


Debdeep Pati Colloquium

Thursday, September 22, 2016 - 2:45pm

Statistics Department Colloquium

Where: LeConte College, Room 210

Speaker: Debdeep Pati

Affiliation: Florida State University, Department of Statistics

Title:  Bayesian community detection and goodness of fit tests in stochastic block models

Abstract: 

In this talk, I focus on two key problems in Bayesian network models.  The first part of the talk deals with clustering the nodes of a network into groups which share a similar connectivity pattern.  Existing algorithms for community detection assume the knowledge of the number of clusters or estimate it a priori using various selection criteria and subsequently estimate the community structure. Ignoring the uncertainty in the first stage may lead to erroneous clustering, particularly when the community structure is vague. I instead propose a coherent probabilistic framework (MFM-SBM) for simultaneous estimation of the number of communities and the community structure. The methodology is shown to outperform recently developed community detection algorithms in a variety of synthetic data examples and in benchmark real-datasets.  In addition, I derive minimax optimal bounds for the Bayes risk, which is novel in the Bayesian context to best of my knowledge. In the second part of the talk, I focus on deriving goodness of fit tests when the number of communities is unknown. The test relies on algebraic geometric techniques, which can potentially be generalized to construct goodness of fit tests in latent class models.


PDF icon Debdeep Pati Colloquium.pdf