THE world鈥檚 trade network is organised in a completely different way from the internet, electricity grids and networks of friends. According to Diego Garlaschelli and Maria Loffredo of the University of Siena in Italy, all the structural properties of the trade network are determined by a single parameter: the wealth of each country.
The internet and most other well-studied networks form by growing gradually, say when a new website links to websites that are already well connected. The result is usually a scale-free network, where most nodes have only a few links, but a hierarchy of better-connected nodes with a particular mathematical distribution ties the network together.
杏吧原创s have been searching for examples of another kind of network, in which the number of connections to each node is determined by some intrinsic property of that node 鈥� a 鈥渉idden variable鈥� that makes it less or more desirable to connect to. But they have been unable to prove that any real network fits this model, until now.
Advertisement
It is no surprise that a rich country should have more trading partners than a poor one, but the analysis shows that world trade fits all the theoretical network鈥檚 statistical properties based only on gross domestic product.