Luc Girardin


Last Name

Girardin

First Name

Luc

ORCID

0000-0002-8979-8228

Organisational unit

03649 - Cederman, Lars-Erik / Cederman, Lars-Erik

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Publications1 - 10 of 16
  • Integrating Data on Ethnicity, Geography, and Conflict: The Ethnic Power Relations Data Set Family
    Item type: Journal Article
    Vogt, Manuel; Bormann, Nils-Christian; Rüegger, Seraina; et al. (2015)
    Journal of Conflict Resolution
  • Nationalism and the Transformation of the State
    Item type: Monograph
    Cederman, Lars-Erik; Girardin, Luc; Müller-Crepon, Carl; et al. (2025)
  • The Train Wrecks of Modernization: Railway Construction and Separatist Mobilization in Europe
    Item type: Journal Article
    Pengl, Yannick I.; Müller-Crepon, Carl; Valli, Roberto; et al. (2026)
    American Political Science Review
    This paper uses the gradual expansion of the European railway network to investigate how this key technological driver of modernization affected ethnic separatism between 1816 and 1945. Combining new historical data on ethnic settlement areas, conflict, and railway construction, we test how railroads affected separatist conflict and successful secession as well as independence claims among peripheral ethnic groups. Difference-in-differences, event study, and instrumental variable models show that, on average, railway-based modernization increased separatist mobilization and secession. These effects concentrate in countries with small core groups, weak state capacity, and low levels of economic development as well as in large ethnic minority regions. Exploring causal mechanisms, we show how railway networks can facilitate mobilization by increasing the internal connectivity of ethnic regions and hamper it by boosting state reach. Overall, our findings call for a more nuanced understanding of the effects of European modernization on nation building.
  • Exploring Inequality and Ethnic Conflict: EPR-ETH and GROWup
    Item type: Book Chapter
    Cederman, Lars-Erik; Girardin, Luc; Wucherpfennig, Julian (2014)
    Peace and Conflict 2014
    This chapter discusses the Ethnic Power Relations (EPR) family of datasets. These resources are available through the online data portal GROWup (Geographic Research On War, unified platform), which is provided by the International Conflict Research (ICR) group at ETH Zürich (see http://growup.ethz.ch). This platform allows users to gain easy access to data on ethnic groups’ political power and conflict behavior around the world from 1946 through 2009. After describing the motivations, development, and design of the data and the portal, we turn to their research applications. Introducing the Research Area and the Need for Data In response to the surge of ethnic conflict in the early 1990s, systematic data collection on ethnic groups and their roles intensified. Previous datasets, such as the Atlas Narodov Mira (Bruk and Apenchenko 1964), were primarily anthropological or focused on linguistic differences alone. The new wave of empirical research was led by Gurr’s Minorities at Risk (MAR) project, which introduced a series of political indicators recording grievances and inequalities focusing on exposed minorities (Gurr 1993a, 1993b, 2000). Based on this evidence, Gurr concluded that members of politically, economically, and culturally disadvantaged groups are more likely to stage protest and rebellion against incumbent governments than those who enjoy a more secure position in society. The MAR dataset quickly became the standard source of systematic data on ethnic groups. Thanks to its comprehensiveness, in terms of geographic coverage and the number of variables, the new data resource has spawned an entire research program that analyzes various aspect of ethnic conflict (Hug 2013).
  • War Did Make States: Revisiting the Bellicist Paradigm in Early Modern Europe
    Item type: Journal Article
    Cederman, Lars-Erik; Galano Toro, Paola; Girardin, Luc; et al. (2023)
    International Organization
    Charles Tilly's classical claim that "war made states" in early modern Europe remains controversial. The "bellicist" paradigm has attracted theoretical criticism both within and beyond its original domain of applicability. While several recent studies have analyzed the internal aspects of Tilly's theory, there have been very few systematic attempts to assess its logic with regard to the territorial expansion of states. In this paper, we test this key aspect of bellicist theory directly by aligning historical data on European state borders with conflict data, focusing on the period from 1490 through 1790. Proceeding at the systemic, state, and dyadic levels, our analysis confirms that warfare did in fact play a crucial role in the territorial expansion of European states before (and beyond) the French Revolution.
  • Computational approaches to conflict research from modeling and data to computational diplomacy
    Item type: Journal Article
    Cederman, Lars-Erik; Girardin, Luc (2023)
    Journal of Computational Science
    This paper offers an account of our own efforts to draw on computational methods to study conflict processes at the macro level. During a first phase, we relied on agent-based modeling in order to capture the complexity of system-level processes. This research yielded a number of publications, but less by way of influence on substantive research and policy making. Therefore, we decided to shift our main focus away from agent-based modeling to spatial computation, which allow for a more direct empirical validation of our results. This second phase of research includes the collection and integration of large amounts of spatiotemporally structured data, which we analyze with more conventional econometric tools. To advance the field of computational diplomacy, we recommend that future search combines agent-based modeling with rigorous empirical validation through the utilization of spatial computation.
  • Nationalism and the Puzzle of Reversing State Size
    Item type: Journal Article
    Cederman, Lars-Erik; Girardin, Luc; Müller-Crepon, Carl (2023)
    World Politics
    Having increased for centuries, territorial state size began to decline toward the end of the nineteenth century and has continued to do so. The authors argue that processes triggered by ethnic nationalism are the main drivers of this development. Their empirical approach relies on time-varying spatial data on state borders and ethnic geography since the nineteenth century. Focusing on deviations from the nation-state ideal, the authors postulate that state internal ethnic fragmentation leads to reduction in state size and that the cross-border presence of dominant ethnic groups makes state expansion more likely. Conducted at the systemic and state levels, the analysis exploits information at the interstate dyadic level to capture specific nationalist processes of border change, such as ethnic secession, unification, and irredentism. The authors find that although nationalism exerts both integrating and disintegrating effects on states' territories, it is the latter impact that has dominated.
  • Growing Sovereignty: Modeling the Shift from Indirect to Direct Rule
    Item type: Journal Article
    Cederman, Lars-Erik; Girardin, Luc (2010)
    International Studies Quarterly
  • Ethnonationalist Triads: Assessing the Influence of Kin Groups on Civil Wars
    Item type: Journal Article
    Cederman, Lars-Erik; Girardin, Luc; Gleditsch, Kristian Skrede (2009)
    World Politics
  • Technical Note: Evaluating Java Development Kits for Agent-Based Modeling
    Item type: Journal Article
    Weidmann, Nils B.; Girardin, Luc (2005)
    Journal of Artificial Societies and Social Simulation
    We present experiments assessing the performance of different Java Development Kits (JDKs) with respect to agent-based models. In our experiments, we measure the execution time of two prototypical agent-based models written in Java under different JDKs and operating systems. Our findings suggest that whereas the impact of the operating system is fairly small, the JDK in use affects performance considerably, with the most recent JDKs performing best. The results of a numerical Java benchmark computed for the same JDKs and operating systems display only a small correlation with these results. In a series of scaling experiments we examine the JDK performance along an increasing model size, again finding a competitive advantage of recent JDKs.
Publications1 - 10 of 16