December 2021 Modeling the social media relationships of Irish politicians using a generalized latent space stochastic blockmodel
Tin Lok James Ng, Thomas Brendan Murphy, Ted Westling, Tyler H. McCormick, Bailey Fosdick
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Ann. Appl. Stat. 15(4): 1923-1944 (December 2021). DOI: 10.1214/21-AOAS1483

Abstract

Dáil Éireann is the principal chamber of the Irish parliament. The 31st Dáil was in session from March 11th, 2011 to February 6th, 2016. Many of the members of the Dáil were active on social media, and many were Twitter users who followed other members of the Dáil. The pattern of Twitter following amongst these politicians provides insights into political alignment within the Dáil. We propose a new model, called the generalized latent space stochastic blockmodel, which extends and generalizes both the latent space model and the stochastic blockmodel to study social media connections between members of the Dáil. The probability of an edge between two nodes in a network depends on their respective class labels, as well as sender and receiver effects and latent positions in an unobserved latent space. The proposed model is capable of representing transitivity and clustering, as well as disassortative mixing. A Bayesian method with Markov chain Monte Carlo sampling is proposed for estimation of model parameters. Model selection is performed using the WAIC criterion and models of different number of classes or dimensions of latent space are compared. We use the model to study Twitter following relationships of members of the Dáil and interpret structure found in these relationships. We find that the following relationships amongst politicians is mainly driven by past and present political party membership. We also find that the modeling outputs are informative when studying voting within the Dáil.

Funding Statement

This work was partially supported by the National Science Foundation under Grant Number SES-1461495 to Fosdick and Grant Numbers SES-1559778 and DMS-1737673 to McCormick. McCormick is also supported by grant number K01 HD078452 from the National Institute of Child Health and Human Development (NICHD). This material is based upon work supported by, or in part by, the U.S. Army Research Laboratory and the U.S. Army Research Office under contract/grant number W911NF-12-1-0379. Murphy and Ng are supported by the Science Foundation Ireland funded Insight Research Centre (SFI/12/RC/2289_P2). The authors would also like to thank the Isaac Newton Institute Program on Theoretical Foundations for Statistical Network Analysis workshop on Bayesian Models for Networks, supported by EPSRC grant number EP/K032208/1.

Acknowledgements

The authors would like to thank the Editor, Associate Editor and reviewers for their useful comments that improved this work. We would also like to thank Professor David Farrell for his advice on relevant research results in Irish politics.

Citation

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Tin Lok James Ng. Thomas Brendan Murphy. Ted Westling. Tyler H. McCormick. Bailey Fosdick. "Modeling the social media relationships of Irish politicians using a generalized latent space stochastic blockmodel." Ann. Appl. Stat. 15 (4) 1923 - 1944, December 2021. https://doi.org/10.1214/21-AOAS1483

Information

Received: 1 December 2020; Published: December 2021
First available in Project Euclid: 21 December 2021

MathSciNet: MR4355082
zbMATH: 1498.62326
Digital Object Identifier: 10.1214/21-AOAS1483

Keywords: Irish politician , latent space stochastic blockmodel , social network analysis

Rights: Copyright © 2021 Institute of Mathematical Statistics

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Vol.15 • No. 4 • December 2021
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