Convergence of European Business Cycles: A Complex Networks Approach

We examine the co-movement patterns of European business cycles during the period 1986-2011, with an obvious focal point the year 1999 that marked the introduction of the common currency, the euro. The empirical analysis is performed within the context of Graph Theory where we apply a rolling window approach in order to dynamically analyze the evolution of the network that corresponds to the GDP growth rate cross-correlations of 22 European economies. The main innovation of our study is that the analysis is performed by introducing what we call the Threshold-Minimum Dominating Set (T-MDS). We provide evidence at the network level and analyze its structure and evolution by the metrics of total network edges, network density, isolated nodes and the cardinality of the T-MDS set. Next, focusing on the country level, we analyze each individual country's neighborhood set (economies with similar growth patterns) in the pre- and post-euro era in order to assess the degree of convergence to the rest of the economies in the network. Our empirical results indicate that despite few economies' idiosyncratic behavior, the business cycles of the European countries display an overall increased degree of synchronization and convergence in the single currency era.