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PAOLO LI DONNI

A Constrained Dynamic Bivariate Poisson Stochastic Block Model for Hospital Network Data

Abstract

Anextendedstochasticblockmodelforclusteringdynamicweightednetworkdataisintroduced,wheretheblockmembershipsarerepresentedbyasequenceoflatentvariablesfollowingaMarkovchain.MotivatedbytheavailabilityoforiginaldataonpatienttransferswithinanetworkofItalianhospitals,weproposetorelyonabivariatePois-sontoexplicitlymodelthedistributionofthedyadsconditionalonthestatesoccupiedbybothnodesinvolvedintherelationatagiventimeoccasion.Inordertoenhancetheinterpretationofthemodelparameters,weproposesuitableconstrainsthatallowtodescribethepropensityofnodestodirectedinteractions.Modelinferenceisbasedonavariationalapproach.