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Abstract Many types of civil unrest, including protest, violent conflict, and rebellion, have been found to be subject to both inter- and intra-state contagion. These spillover effects are conventionally tested through the application of parametric structural models that are estimated using observational data. Drawing on research in methods for network analysis, we note important challenges in conducting causal inference on contagion effects in observational data. We review a recently developed non-parametric test—the “split-halves test”—that is robust to confounding and apply the test to replication data from several recent studies in which researchers tested for contagion in civil unrest. We find that about half the time findings in the published literature fail to replicate with the split-halves test. Across ten total replications, we do not see strong patterns in terms of which results do and do not replicate. We do, however, find evidence for general contagion in six of the replications, indicating that contagion is a prevalent phenomenon in civil unrest. As such, we recommend that researchers (1) use the split-halves test as a general-purpose robustness check for parametric models of contagion in the study of civil unrest, and (2) consider modeling contagion in research on civil unrest.
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Reactivation of Cumbre Vieja volcano
After 50 years of repose, Cumbre Vieja volcano—historically the most active of the Canary Islands—entered an eruptive episode on 19 September 2021, forcing the evacuation of ∼6400 residents and destroying infrastructure worth more than 400 million euros. The volcanic unrest began in 2017 but accelerated only 8 days before the onset of the eruption. This behavior, characterized by comparatively protracted periods of quiescence and unrest, is at odds with global systematics for basaltic volcanoes ( 1 ).
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- Award ID(s):
- 1944723
- PAR ID:
- 10324731
- Date Published:
- Journal Name:
- Science
- Volume:
- 374
- Issue:
- 6572
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 1197 to 1198
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.abm9423
