Core/periphery structure versus clustering in international weblogs

When analyzing social networks, centrality and community identification are among the most popular topics for researchers. Depending on their motivation and the resulting hypothesis, they usually focus on one of these two structural properties, leaving the other aspect aside. In this paper we investigate the relation between structural centralization, which follows a core/periphery model, and structural clustering, which is given by more or less disjoint cohesive groups. We present our concept of Group Adjacency Matrices for graphical evaluations of such structures, and analyze these properties in networks of top blogs in six different languages. We show that the two properties are present in parallel in our datasets, making the respective identification more difficult. We want to raise awareness of this potential issue, and demonstrate that the knowledge about the clustering structure in a network can be utilized to make the analysis of the core/periphery structure more reliable.