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Is culture the glue that holds the social structures of society together? Or are there “culture wars” that fundamentally divide us? Clearly, the answer is somewhere in the middle, and trying to understand precisely how culture and social structure interrelate to unite or divide remains a core sociological endeavor. Social network analysis alone cannot resolve such an enormous puzzle, but its methods provide important tools for formalizing a jointly structural and cultural approach to studying society. In this chapter, we conclude Part II on Seeing Structure by outlining efforts to see dualities in the connections between structure and culture – that is, to study how enduring patterns of interaction interrelate with shared understandings, tastes, meanings, and other attitudinal measures. We also discuss the structural analysis of meanings themselves and the application of social network techniques to cultural phenomena.
Social structure is enacted by individuals. At the same time, social structure channels individuals into opportunities for action and provides schemas for helping them make sense of these actions. Structure is therefore both the medium through which individuals realize fundamental human drives as well as the collective outcome of the actions that others take and have taken in the past. This ongoing interplay of agency and structure is called structuration. While predictive models outlined in Part III test specific structuration mechanisms, here we cover more inductive approaches and present various micro-level ideas about what drives people to form and break (certain types of) ties. We then introduce the reader to ego-centric network analysis as an important technique that illuminates many of these structuration processes with individual-level data.
Having lived through a global pandemic, or more trivially, having seen online memes “go viral,” we are all intuitively familiar with the spread of things through network ties. Diseases, memes, used books, and cash are ready examples of things passed from one person to another. Somewhat less familiar, perhaps, is that a fundamentally similar mechanism underlies many of our social behaviors. Understanding such processes is therefore related to understanding how anything – information, rumors, diseases, and so on – diffuses through a system. Key questions include: How does a network structure as a whole (its topology) affect the diffusion process? And how does a node’s position in this structure affect the likelihood of transmitting and receiving flows?
Whereas previous chapters have focused on networks as conduits through which important resources and influences flow, this chapter provides a more in-depth account of the positional approach to networks. In doing so, we move away from conceptualizing social structures as more or less cohesive and integrated groups, cliques, communities, etc., toward a view of social structures as comprised of role structures. To use the baseball analogy, in moving toward a more positional view of networks, we shift from seeing teams as interacting individual players with relations with one another to seeing players as enacting the game through an interrelated set of positions on the field that come with role expectations. Thus, as depicted in our view of social structure in Figure 2.3, we begin to move upward and to the right – that is, toward higher levels of structure and greater levels of conceptual abstraction. Doing so requires a different set of methods, which we introduce in this chapter.
Preservation of stochastic orders through the system signature has captured the attention of researchers in recent years. Signature-based comparisons have been made for the usual stochastic order, hazard rate order, and likelihood ratio orders. However, for the mean residual life (MRL) order, it has recently been proved that the preservation result does not hold true in general, but rather holds for a particular class of distributions. In this paper, we study whether or not a similar preservation result holds for the mean inactivity time (MIT) order. We prove that the MIT order is not preserved from signatures to system lifetimes with independent and identically distributed (i.i.d.) components, but holds for special classes of distributions. The relationship between these classes and the order statistics is also highlighted. Furthermore, the distribution-free comparison of the performance of coherent systems with dependent and identically distributed (d.i.d.) components is studied under the MIT ordering, using diagonal-dependent copulas and distorted distributions.
Images can be powerful; and, as the saying goes, “with great power comes great responsibility.” Today, the world is suffused with images through various media, and people have come to expect pictures to tell them stories. With increased computational power, images of quantitative data are increasingly part of the “stories” one commonly sees and are powerful in communicating research findings. Many of these images are informative and effective; others are confusing, convey little actual information, or, sadly, are used to intentionally mislead for ideological reasons. Network science has always used compelling images to tell stories about structures, and the field is therefore particularly suited to make the most use of this era of data visualization. But given the vastly expanded palette of visualization available today, how does the researcher decide what is a good network image?
Where do networks come from? Numerous theories direct us to the causes of networks (e.g., homophily, triadic closure, physical proximity), some emphasizing outside factors (exogenous causes) and others emphasizing point-in-time network structure (endogenous causes) as shaping a network’s future trajectory. So far, we have examined such causal theories using cross-sectional snapshots in the form of metrics (centrality, density), partitions (clusters), and maps or spaces (visualization). These approaches generally suffer from a lack of stochastic features and observational overdetermination: for example, we observe a pattern in a given school on a given day, but that pattern could result from actor preferences and constraints in the setting. Disentangling such effects requires an inferential approach to probabilistically examine various effects. To the extent that we want to identify causal forces shaping the networks, understanding the unfolding of relations in time – how the individual ties in a network (the dyads joined by one or more relations) and the entire structure of these relations emerge and evolve – is crucial for testing network theories.
Stop. Take a moment to look around. What do you see? No matter where you are, you are likely perceiving a world consisting of things. Maybe you are reading this book in a coffee shop, and if so, you probably see people, cups, books, chairs, and so on. You see a world of objects with properties, yourself included: white cups are on wooden tables, people sitting in chairs are reading books and talking with one another. At the same time, you are a subject, responding to this world and actively bringing yourself and these objects into interrelation. And yet, the world of objects with properties that you are perceiving is but one slice of a complex reality.
Knowing the burden of severe disease caused by influenza is essential for disease risk communication, to understand the true impact of vaccination programmes and to guide public health and disease control measures. We estimated the number of influenza-attributable hospitalisations in Spain during the 2010–2011 to 2019–2020 seasons – based on the hospitalisations due to severe acute respiratory infection (SARI) in Spain using the hospital discharge database and virological influenza information from the Spanish Influenza Sentinel Surveillance System (SISSS). The weekly numbers of influenza-attributable hospitalisations were calculated by multiplying the weekly SARI hospitalisations by the weekly influenza virus positivity, obtained from the SISSS in each season, stratified by age group and sex. The influenza-related hospitalisation burden is age-specific and varies significantly by influenza season. People aged 65 and over yielded the highest average influenza-attributable hospitalisation rates per season (615.6 per 100,000), followed by children aged under 5 (251.2 per 100,000). These results provide an essential contribution to influenza control and to improving existing vaccination programmes, as well as to the optimisation and planning of health resources and policies.
We conducted a retrospective, analytical cross-sectional and single-centre study that included 190 hospitalised COVID-19 patients in the Fujian Provincial Hospital South Branch between December 2022 and January 2023 to analyse the correlation of viral loads of throat swabs with clinical progression and outcomes. To normalise the Ct value as quantification of viral loads, we used RNase P gene as internal control gene and subtracted the Ct value of SARS-CoV-2 N gene from the Ct value of RNase P gene, termed △Ct. Most patients were discharged (84.2%), and only 10 (5.6%) individuals who had a lower △Ct value died. The initial △Ct value of participants was also significantly correlated with some abnormal laboratory characteristics, and the duration time of SARS-CoV-2 was longer in patients with severe symptoms and a lower △Ct value at admission. Our study suggested that the △Ct value may be used as a predictor of disease progression and outcomes in hospitalised COVID-19 patients.
A set of vertices in a graph is a Hamiltonian subset if it induces a subgraph containing a Hamiltonian cycle. Kim, Liu, Sharifzadeh, and Staden proved that for large $d$, among all graphs with minimum degree $d$, $K_{d+1}$ minimises the number of Hamiltonian subsets. We prove a near optimal lower bound that takes also the order and the structure of a graph into account. For many natural graph classes, it provides a much better bound than the extremal one ($\approx 2^{d+1}$). Among others, our bound implies that an $n$-vertex $C_4$-free graph with minimum degree $d$ contains at least $n2^{d^{2-o(1)}}$ Hamiltonian subsets.
Statistical profiling of job seekers is an attractive option to guide the activities of public employment services. Many hope that algorithms will improve both efficiency and effectiveness of employment services’ activities that are so far often based on human judgment. Against this backdrop, we evaluate regression and machine-learning models for predicting job-seekers’ risk of becoming long-term unemployed using German administrative labor market data. While our models achieve competitive predictive performance, we show that training an accurate prediction model is just one element in a series of design and modeling decisions, each having notable effects that span beyond predictive accuracy. We observe considerable variation in the cases flagged as high risk across models, highlighting the need for systematic evaluation and transparency of the full prediction pipeline if statistical profiling techniques are to be implemented by employment agencies.