An Ordinal Latent Variable Model of Conflict Intensity

Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics Volume 1: Long Papers, pages 4817–4830 July 9-14, 2023 ©2023 Association for Computational Linguistics An Ordinal Latent Variable Model of Conflict Intensity Niklas StoehrQ Lucas Torroba Hennigen@ Josef ValvodaD Robert WestN Ryan CotterellQ Aaron ScheinR QETH Zürich @MIT DUniversity of Cambridge NEPFL RThe University of Chicago niklas.stoehr@inf.ethz.ch lucastor@mit.edu jv406@cam.ac.uk robert.west@epfl.ch ryan.cotterell@inf.ethz.ch schein@uchicago.edu Abstract Measuring the intensity of events is crucial for monitoring and tracking armed conflict. Advances in automated event extraction have yielded massive data sets of “who did what to whom” micro-records that enable data- driven approaches to monitoring conflict. The Goldstein scale is a widely-used expert-based measure that scores events on a conflictual– cooperative scale. It is based only on the action category (“what”) and disregards the subject (“who”) and object (“to whom”) of an event, as well as contextual information, like associated casualty count, that should contribute to the perception of an event’s “intensity”. To address these shortcomings, we take a latent variable- based approach to measuring conflict intensity. We introduce a probabilistic generative model that assumes each observed event is associated with a latent intensity class. A novel aspect of this model is that it imposes an ordering on the classes, such that higher-valued classes denote higher levels of intensity. The ordinal nature of the latent variable is induced from naturally or- dered aspects of the data (e.g., casualty counts) where higher values naturally indicate higher intensity. We evaluate the proposed model both intrinsically and extrinsically, showing that it obtains good held-out predictive performance. https://github.com/niklasstoehr/ ordinal-conflict-intensity 1 Introduction On a scale from −10 for conflictual to +10 for cooperative, which of the following events should be considered more “intense”: “Soldiers injured two civilians” or “Rebels detained fifty soldiers”? Measuring the intensity of events is crucial for monitoring and tracking armed conflict. Ad- vances in the automated collection and coding of events have produced massive and systematized data sets of micro-records that enable data-driven CAMEO code action name Goldstein value avg. # casualties 19 fight -10.0 9.31 20 mass violence -10.0 42.20 18 assault -9.0 11.47 15 force posture -7.2 0.13 17 coerce -7.0 1.44 14 protest -6.5 2.06 13 threaten -6.0 0.13 10 demand -5.0 0.01 12 reject -4.0 0.00 16 reduce relations -4.0 0.00 9 investigate -2.0 0.04 11 disapprove -2.0 0.03 1 public statement 0.0 0.19 4 consult 1.0 0.03 2 appeal 3.0 0.00 5 diplom cooperation 3.5 0.03 3 intent cooperate 4.0 0.05 8 yield 5.0 0.10 6 material cooperation 6.0 0.01 7 provide aid 7.0 0.00 Table 1: The The Goldstein scale is an expert-based intensity ranking of the 20 CAMEO action categories ranging between −10.0 (conflictual) to +10.0 (cooper- ative). The scale disregards casualty counts that are typ- ically considered in conflict assessment. Here, we dis- play casualty counts as reported in the NAVCO dataset. approaches to monitoring conflict. While the “in- tensity” of a given event has traditionally been assessed by human expert raters, the tremendous quantity of …

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