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Research Stay at Princeton University

29/1/2015

From mid-March, I will be in Princeton (New Jersey) for a research stay. Prof. Miguel Centeno, chair of Princeton University's Sociology Department, invited me to visit the research community Global Systemic Risk at the Princeton Institute for International and Regional Studies.

The logo of Global Systemic Risk, representing annual shipping lanes.

The common goal of the interdisciplinary research group, which involves scientists from many fields, including computer science, economics, engineering, history, philosophy, mathematics, physical sciences, psychology, political science, and sociology, is to "focus on the robustness and fragility of global human-made organizational systems and is concerned with risks that have short- to medium-term likelihood and consequences". They argue that "[t]he interdependence of massive global interactions and structures has caused systemic risk to increase exponentially in recent times. Tangible risks—in systems as diverse as energy exploration and production, electricity transmission, computer networks, healthcare, food and water supplies, transportation networks, commerce, and finance—now threaten global political, economic, and financial systems that affect citizens of every nation. As a result, the study of risk has the potential to become an important and influential academic and policy field."

I am looking forward to an exciting collaboration with Prof. Centeno and his colleagues at Princeton University.

New Working Paper available online

29/1/2015

A draft version of my paper The Spatial Structure of Transnational Human Activity is now available online in the arXiv.

Starting from conflictive predictions of hitherto disconnected debates in the natural and social sciences, this paper contains the – to my knowledge – first encompassing analysis of the spatial structure of human activity beyond nation-state borders worldwide (a) across eight types of mobility and communication and (b) in its development over time. It is shown that contrary to what popular terms like “death of distance” and “end of geography” suggest, the spatial structure of transnational human activity is still heavily shaped by physical space. I demonstrate that the relation between activity and distance follows a specific mathematical pattern that can also be found in the movements of many animal species as well as local-scale human motion: Lévy flights with heavy tails that obey power laws. This pattern is also shown to remain remarkably stable over time. The figure on the right shows what a Lévy flight typically looks like: the path of a walker who takes many small and few long steps and changes his direction randomly in between.

A Lévy flight

The map below shows exemplarily one type of communication that is analyzed in the paper: transnational Facebook friendships. The black lines denote the country pairs with the highest number of Facebook friendships. For the purposes of this study, they constitute the equivalent of the steps the random walker takes in the Lévy flight figure above. (NB: The Facebook data was obtained from an interactive graph, converted into a network matrix and graphically mapped using Manish Nag's fantastic free software SONOMA).

A Map of Transnational Facebook Friendships

The third figure below shows the spatial structure of these Facebook friendships. The x-axis shows the distance (in km) and the y-axis states the probability of a transnational Facebook friendship to occur. The blue circles denote binned observations and the black line is a fitted power-law curve. The inset shows the same observations on logarithmic axes, on which the power-law curve forms a straight line.

The Spatial Structure of Transnational Facebook Friendships

As both the graph itself and the goodness-of-fit measure R² show, the power-law fits the observations almost perfectly. In the logged version, the observations cluster closely around the power-law line and the R²=.968 is only slightly below the perfect fit of R²=1.
This finding (which also holds for other types of mobility and communication under study) is clearly at odds with the common notion of a "death of distance" or an "end of geography" in structuring social relations.

For more details just have a look at the paper.

Paul Valéry, the first social network analyst?

29/1/2015

While it appears to be relatively common for social scientists to reconstruct social networks of characters within literary works (see for example the network study of the characters in Dante's inferno by Amedeo Cappelli and colleagues or the social graph of the characters in the Marvel comics universe), or to analyse the real-world social networks of authors (see for example Adam Obeng's work on William Godwin's acquaintance networks), to my knowledge, little attention has been given to explicit or implicit occurences of social network analysis within the substance of world literature itself. I just stumbled upon this interesting section in the French essayist Paul Valéry's 1896 La soirée avec M. Teste that describes the narrator's thoughts upon observing a theater audience (which evidently stands for society in general):

Chacun était à sa place, libre d’un petit mouvement. Je goûtais le système de classification, la simplicité presque théorique de l’assemblée, l’ordre social. J’avais la sensation délicieuse que tout ce qui respirait dans ce cube, allait suivre ses lois, flamber de rires par grands cercles, s’émouvoir par plaques, ressentir par masses des choses intimes, - uniques, - des remuements secrets, s’élever à l’inavouable! J’errais sur ces étages d’hommes, de ligne en ligne, par orbites, avec la fantaisie de joindre idéalement entre eux, tous ceux ayant la même maladie, ou la même théorie, ou le même vice...

This paragraph made me wonder whether Paul Valéry must be considered the first social network analyst. Isn't connecting people who have something in common via ideal lines while leaving those who have nothing in common disconnected exactly what network analysts do today? After all, network studies in epidemiology connect people suffering from the same maladie, studies of co-citation networks allow for following the bonds between people with the same théorie, and network analyses of mafia clans describe connections between those who have fallen for the same vice. Thus, in a way, Valery described as a fantaisie in 1896 what network analysts would actually do in the future, decades before Jacob L. Moreno's 1930s invention of sociometry and even longer before John A. Barnes' first mentioning of the term "social network" in 1954.

On a sidenote, Paul Valéry started writing La soirée avec M. Teste in 1895 in the same house (No. 9, Rue de la Vieille-Intendance in Montpellier) in which Auguste Comte, one of the founding fathers of sociology, was born a century earlier, in 1798. What a small world.

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Research Stay at Princeton University

New Working Paper available online

Paul Valéry, the first social network analyst?

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