Since few states are able to produce all of their own military hardware, a majority of countries’ military systems rely on weapon imports. The structure of the international defense technology exchange network remains an important puzzle to understand, along with the factors that drive its evolution. Drawing on a political economy model of arms supply, we propose a new network-oriented explanation for the worldwide transactions of major conventional weapons in the period after World War II. Using temporal exponential random graph models, our dynamic approach illustrates how network dependencies and the relative weighting of economic versus security considerations vary over time. One of our major results is to demonstrate how security considerations started regaining importance over economic ones after 2001. Additionally, our model exhibits strong out-of-sample predictive performance, with network dependencies contributing to model improvement especially after the Cold War.

As Covid-19 spreads around the world, international actors, including the United Nations, have called for a stop to armed conflict to facilitate efforts to fight the pandemic. At the same time, coronavirus may also trigger and intensify armed conflict due to its negative economic consequences and by offering windows of opportunity to opposition movements to attack distracted and weakened incumbents. We use real-time data on the spread of Covid-19, governmental lockdown policies, and battle events to study the causal short-term effect of the pandemic on armed conflict. Our results suggest that both the spread of Covid-19 and lockdown policies exhibit a global Null effect with considerable regional heterogeneity. Most importantly, governmental lockdowns have increased armed conflict in the Middle East. In contrast, reported combat has decreased in Southeast Asia and the Caucasus as the pandemic has spread.

The ballot structure of German Bundestag elections allows two votes: one for a constituency candidate and the second for a party list. About one-fifth of the voters usually split their ticket. Several hypotheses are derived about incentives for ticket splitting and tested with survey data from a 1998 pre-election poll. We argue that an explanation of split tickets in the German system has to take into account both party rankings and coalition preferences. One of the most important incentives is a preference or top ranking of a minor party like the FDP or Greens, if it is combined with a preference for a coalition with either the CDU/CSU or SPD. Contrary to this finding, the hypothesis of threshold insurance voting of CDU/CSU or SPD supporters choosing the party list of their prospective minor coalition partner is rejected for the 1998 election.

The analysis of voter transitions is an important area of electoral studies. A main strategy is to use aggregate data provided by the offices of statistics regarding districts, precincts, communities etc. and to rely on ecological inference. Ecological inference, however, is plagued by the well-known indeterminacy problem. In this article, we present the so far most extensive systematic empirical comparison of commonly used approaches for ecological inference of the analysis of voter transitions. Our evaluation is based on diverse simulations for multiple assumptions and scenarios. Based on recent election data for the German metropolitan city Munich, we are able to show that an application of the hierarchical multinomial-Dirichlet model, which is implemented in the R-library eiPack, exhibits the best overall estimation performance. Other prominent approaches frequently used by practitioners, e.g. the Thomsen logit approach, proved to be inconsistent. Furthermore, we demonstrate that appropriate data preprocessing is crucial for achieving reliable results.

Abstract.  Does the European Union (EU) represent a new political order replacing the old nation‐states? The assessment of the real character of political orders requires the identification of political key actors and of the specific structure of their interactions. Transgovernmental networks have been considered to be one of the most important features of EU integration. Unfortunately, the network structures, processes and the impact of these informal horizontal inter‐organisational relations between nation‐states are mostly unknown. The main objective of this article is to measure and explain the selective pattern of informal bilateral relations of high officials of the EU Member States’ ministerial bureaucracies on the occasion of an EU Intergovernmental Conference. The quantitative data used rely on standardised interviews with 140 top‐level bureaucrats. The statistical estimation of network choices is based on recent developments of exponential random graph models.