Cyclic motifs in the Sardex monetary network

• Published in: Nature human behaviour 2018-11, Vol.2 (11), p.822-829
• Main Authors: Iosifidis, George, Charette, Yanick, Airoldi, Edoardo M., Littera, Giuseppe, Tassiulas, Leandros, Christakis, Nicholas A.
• Format: Article
• Language: English
• Subjects: 4014/2801; 706/689; Banking system; Behavioral Sciences; Biomedical and Life Sciences; Centralization; Community; Credit systems; Currency; Decentralization; Density; Economic activity; Economic systems; Experimental Psychology; Letter; Life Sciences; Microeconomics; Monetary systems; Money; Network analysis; Neurosciences; Personality and Social Psychology; Robustness; Social problems; Time use; Transactions
• ISSN: 2397-3374; 2397-3374
• DOI: 10.1038/s41562-018-0450-0

From decentralized banking systems to digital community currencies, the way humans perceive and use money is changing 1 – 3 , thus creating novel opportunities for solving important economic and social problems. Here, we study Sardex, a fast-growing community currency in Sardinia (involving 1,477 businesses arrayed in a network with 48,170 transactions) using network analysis to shed light on its operation. Based on our experience with its day-to-day operations, we propose performance metrics tailored for Sardex but also to similar economic systems, introduce criteria for identifying prominent economic actors and investigate the interplay between network structure and economic robustness. Leveraging new methods for quantifying network ‘cyclic density’ and ‘ k -cycle centrality,’ we show that geodesic transaction cycles, where money flows in a circle through the network, are prevalent and that certain nodes have a pivotal role in them. We analyse the transactions within cycles and find that the economic turnover of the involved firms is higher, and that excessive currency and debt accumulations are lower. We also measure a similar, but secondary, effect for nodes and edges that serve as intermediaries to many transactions. These metrics are strong indicators of the success of such mutual credit systems at individual and collective levels. Analyses of transactions in a new monetary system (Sardex community currency) reveal that transaction cycles increase in prevalence over time and that economic activity within these cycles is higher compared to linear transactions through the network.