Social networks: who counts most?

As digital social networks increasingly shape how we behave, understanding their mechanics has become a major scientific challenge. The effort is not new, though: since the 20th century, the social sciences have used graph theory to model relationships between individuals. With the rise of computing in the 1970s, complex calculations became feasible and these analyses gained new momentum.

Countless systems, from international trade and the spread of viruses to, of course, social relationships between individuals, can be represented graphically as diagrams, in the form of ‘nodes’ connected by ‘links’. 

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Dialogues économiques is a digital journal published by the Aix-Marseille School of Economics (AMU, CNRS, EHESS, Centrale Méditerranée). A gateway between academic research and society, Dialogues économiques provides all citizens with the keys to economic reasoning. Articles are published every two weeks.

Using diagrams in the social sciences

In the social sciences, network analysis makes it possible to explain behaviour not just by individual characteristics - age, class, gender - but by a person’s position in their network. In 1974, for example, American sociologist Mark Granovetter showed the importance of personal ties in job search strategies¹. This finding highlights the nuances in typical labour-market analyses and helps explain why, with the same qualifications, some people struggle more to find work because they do not have access to the requisite networks. Understanding how information circulates in a network is therefore essential to many social and economic policies.

Networks in development economics

In 2013, a team of four economists - including future Nobel laureates Esther Duflo and Abhijit Banerjee published a major study on the rollout of microcredit² -which lends small sums to people excluded from traditional banking or reliant on usurious loans. The aim is to boost productive activities and living conditions. In 2006, the microfinance organization Bharatha Swamukti Samsthe (BSS) launched a microcredit program in about a hundred rural villages in Karnataka, southwest India. Because the teams could not knock on every door, BSS took a familiar approach: in each village, inform the person deemed most influential - a teacher, a village chief, a shopkeeper - who would then convene local meetings with nearby farmers to publicise the program.