Interest group networks in the European Union

Interest group networks are crucial for understanding EU integration, policymaking and interest representation. Yet, comparative analysis of interest organization networks across EU policy areas is limited. This study provides the first large-scale investigation of interest group information networks across all EU policy-domains. We argue that interest groups prioritize access to trustworthy and high-quality information coming from partners with shared policy goals. Thus, interest organizations form network ties with other organizations if the latter are from the same country, represent the same type of interest, or are policy insiders. The effect of these three factors varies across policy-domains depending on the extent to which the institutional setting assures equal and broad organizational access to decision-making. Our empirical analysis operationalises information ties as Twitter-follower relationships among 7,388 interest organizations. In the first step of the analysis, we use Exponential Random Graph Models (ERGMs) to examine tie formation in the full network and across forty policy-domains. We find strong but variable effects of country and interest type homophily and policy-insiderness on the creation of network ties. In the second step, we examine how the effect of these three variables on tie formation varies with policy-domain characteristics. We find that shared interest type and policy-insiderness are less relevant for tie formation in (re-)distributive and especially regulatory policy-domains characterised by more supranational decision-making. Sharing an interest type and being a policy insider matters more for tie formation in foreign and interior policies where decision-making is more intergovernmental. The effect of country homophily effect is less clearly related to policy type and decision-making mode. Our findings emphasize the importance of institutional and policy context in shaping interest group networks in the EU.