Hub and Authorities in the World Trade Network
Link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100338
The article discusses a research in which a well-defined weighted hyperlink-included topic search (HITS) algorithm was used to calculate the values of the hub and authority for each country of the world trade network (WTN). The first empirical characterization of the world trade web as a network built upon the trade relationships between countries throughout the world was presented by Serrano and Boguna in 2003. Since then, a major research topic in social network studies has been the investigation of the effect of ranking algorithms on the behavior of networked systems. The HITS algorithm is used to rank the importance of a node in a complex directed network using authority and hub values. In its original meaning, a node with a high authority value is pointed to by many other nodes with high hub values, and a node with a high hub value points to many nodes with high authority values. In an economic sense and as defined in attempt to describe the patterns of international trade, the word “hub”, while not strictly defined, is used to indicate the countries that have a large number of outgoing links with a large amount of trade – in other words, they export large amounts of goods and services to other countries. Likewise, a high “authority” value in this economic context is used to indicate a country with significant imports from large hub countries.
In the WTN, countries are the nodes and the exports/imports among the countries are the links. The researchers in this paper were able to quantitatively discuss the WTN’s economic hubs and its topology changes over time through mathematically defined hubs calculated from the weighted HITS algorithm. Specifically, the following conclusions were made based on the analysis of the study. First, the United States has been the largest destination of world exports and therefore, has been the largest economic authority in the WTN over the last 21 years. A major change in the structure of the WTN occurred with China’s dramatic rise in trade volume and number of trading partners since 2001. This was demonstrated through the study’s HITS networks analysis as China had the world’s largest hub value and third largest authority value, indicating its gradual transformation from the “factory of the world” to the “market of the world.” European countries experienced decreased hub and authority values since it was found to trade mostly within the EU. Japan’s transition from an export-driven economy in its high economic growth era in the latter half of the twentieth century to a more economically balanced nation is also consistent with Japan’s slowly increasing authority score and declining hub value. In conclusion, the study conducted in the paper effectively showed the evolution of WTN over the last 21 years, explaining the changes in terms of hub-authority and found that some typical behaviors are consistently explained by changes in countries and international relations. This consistency suggests the implication of a possible numerical model that can be used to predict hub-authority values of WTN.
The paper discussed an interesting application of network studies, specifically on the topic of link analysis through hubs and authorities. The class discusses the role of link analysis in a network in the field of information retrieval and its essentiality in enabling better search results. One method of making the search results more precise was through a ranking procedure, in which pages were the authorities for the query and high-value lists were the hubs for the query. The intuition behind hubs and authorities is based on the idea that pages can play a powerful endorsement role without themselves being heavily endorsed. This same intuition and link analysis through hubs and authorities was used in the study discussed in the paper, with the only difference being that it demonstrated the usefulness of such analysis even in an economic context. The paper was one example of the fact that link analysis serves a purpose beyond that of providing better search results, but rather, can be used in other real-world contexts and networks as well, such as in analyzing and possibly even predicting the changes of the world trade network.