Multinetwork of international trade: A commodity-specific analysis

TL;DR

This paper analyzes the structure of commodity-specific international trade networks, revealing their heterogeneity, differences from aggregate networks, and evolving commodity roles, with implications for understanding trade specialization.

Contribution

It provides a detailed topological analysis of commodity-specific trade networks and introduces a method to characterize multinetworks as aggregated layers.

Findings

Commodity-specific networks have highly heterogeneous link-weight distributions.

Aggregate trade network results from many weak links maintaining connectivity.

Commodity roles in the trade network are becoming more dissimilar over time.

Abstract

We study the topological properties of the multinetwork of commodity-specific trade relations among world countries over the 1992-2003 period, comparing them with those of the aggregate-trade network, known in the literature as the international-trade network (ITN). We show that link-weight distributions of commodity-specific networks are extremely heterogeneous and (quasi) log normality of aggregate link-weight distribution is generated as a sheer outcome of aggregation. Commodity-specific networks also display average connectivity, clustering, and centrality levels very different from their aggregate counterpart. We also find that ITN complete connectivity is mainly achieved through the presence of many weak links that keep commodity-specific networks together and that the correlation structure existing between topological statistics within each single network is fairly robust and mimics that of the aggregate network. Finally, we employ cross-commodity correlations between link weights to build hierarchies of commodities. Our results suggest that on the top of a relatively time-invariant ``intrinsic" taxonomy (based on inherent between-commodity similarities), the roles played by different commodities in the ITN have become more and more dissimilar, possibly as the result of an increased trade specialization. Our approach is general and can be used to characterize any multinetwork emerging as a nontrivial aggregation of several interdependent layers.