Look Who's Talking: Bipartite Networks as Representations of a Topic Model of New Zealand Parliamentary Speeches

Quantitative methods to measure the participation to parliamentary debate and discourse of elected Members of Parliament (MPs) and the parties they belong to are lacking. This is an exploratory study in which we propose the development of a new approach for a quantitative analysis of such participation. We utilize the New Zealand government's digital Hansard database to construct a topic model of parliamentary speeches consisting of nearly 40 million words in the period 2003-2016. A Latent Dirichlet Allocation topic model is implemented in order to reveal the thematic structure of our set of documents. This generative statistical model enables the detection of major themes or topics that are publicly discussed in the New Zealand parliament, as well as permitting their classification by MP. Information on topic proportions is subsequently analyzed using a combination of statistical methods. We observe patterns arising from time-series analysis of topic frequencies which can be related to specific social, economic and legislative events. We then construct a bipartite network representation, linking MPs to topics, for each of four parliamentary terms in this time frame. We build projected networks (onto the set of nodes represented by MPs) and proceed to the study of the dynamical changes of their topology, including community structure. By performing this longitudinal network analysis, we can observe the evolution of the New Zealand parliamentary topic network and its main parties in the period studied.Comment: 28 pages, 12 figures, 3 table

Degree distributions of bipartite networks and their projections

Bipartite (two-mode) networks are important in the analysis of social and economic systems as they explicitly show conceptual links between different types of entities. However, applications of such networks often work with a projected (one-mode) version of the original bipartite network. The topology of the projected network, and the dynamics that take place on it, are highly dependent on the degree distributions of the two different node types from the original bipartite structure. To date, the interaction between the degree distributions of bipartite networks and their one-mode projections is well understood for only a few cases, or for networks that satisfy a restrictive set of assumptions. Here we show a broader analysis in order to fill the gap left by previous studies. We use the formalism of generating functions to prove that the degree distributions of both node types in the original bipartite network affect the degree distribution in the projected version. To support our analysis, we simulate several types of synthetic bipartite networks using a configuration model where node degrees are assigned from specific probability distributions, ranging from peaked to heavy-tailed distributions. Our findings show that when projecting a bipartite network onto a particular set of nodes, the degree distribution for the resulting one-mode network follows the distribution of the nodes being projected on to, but only so long as the degree distribution for the opposite set of nodes does not have a heavier tail. Furthermore, we show that bipartite degree distributions are not the only feature driving topology formation of projected networks, in contrast to what is commonly described in the literature.Comment: 14 pages, 5 figures, 3 table

Transitivity and degree assortativity explained: The bipartite structure of social networks

Dynamical processes, such as the diffusion of knowledge, opinions, pathogens, "fake news", innovation, and others, are highly dependent on the structure of the social network on which they occur. However, questions on why most social networks present some particular structural features, namely high levels of transitivity and degree assortativity, when compared to other types of networks remain open. First, we argue that every one-mode network can be regarded as a projection of a bipartite network, and show that this is the case using two simple examples solved with the generating functions formalism. Second, using synthetic and empirical data, we reveal how the combination of the degree distribution of both sets of nodes of the bipartite network --- together with the presence of cycles of length four and six --- explains the observed levels of transitivity and degree assortativity in the one-mode projected network. Bipartite networks with top node degrees that display a more right-skewed distribution than the bottom nodes result in highly transitive and degree assortative projections, especially if a large number of small cycles are present in the bipartite structure.Comment: 9 pages, 6 figure

Laien und Experten während der ersten Medienrevolution. Transformation der christlichen Wissensordnung in der frühen und späteren Reformation

editorial reviewe

IEG DH Lab at NetSciX 2020

by Demival Vasques Filho I just returned from Japan, where I attended the NetSciX (the Winter edition of NetSci) conference. It was an enjoyable event, with inspiring presentations and discussions. Here, I will share with you some of my perceptions about it! It seems that the humanities still have a low presence in conferences on network science. I was the only person from a History (and humanities) department/institution to raise my hand when a quick and informal poll took place at the ..

Research visit in New Zealand: Modelling the spread of COVID-19 on higher-order networks

At the beginning of March, I went to New Zealand for a research visit with a planned duration of four weeks. This visit was part of a collaboration involving the IEG DH Lab and Te Pūnaha Matatini, a New Zealand centre of research excellence for complex systems and data science hosted by the University of Auckland’s Department of Physics. The main goal of the visit was to further develop our research on the structure of higher-order networks, that is, networks which account for interactions ..

Imperial Commoners in Brazil and West Africa (1640–1822): A Global History from a Correspondence Network Perspective

By Agata Bloch and Demival Vasques Filho After a couple of attempts, we have finally received the exciting news that our project has been recommended for funding by the Polish National Science Center! Over the next four years, we will study the communication patterns of imperial commoners (non-elite actors) who developed similar characteristics, narratives, and thought strategies in different areas of the vast Atlantic Portuguese Empire. We are interested not only in how these commoners gen..

Moderation and authority-building process: the dynamics of knowledge creation on history subreddits

peer reviewe