Statistical sightings of better angels: Analysing the distribution of battle-deaths in interstate conflict over time
| Author | Céline Cunen,Nils Lid Hjort,Håvard Mokleiv Nygård |
| Date | 01 March 2020 |
| Published date | 01 March 2020 |
| DOI | 10.1177/0022343319896843 |
| Subject Matter | Research Articles |
Research Articles
Statistical sightings of better angels:
Analysing the distribution of battle-deaths
in interstate conflict over time
Ce
´line Cunen
Department of Mathematics, University of Oslo
Nils Lid Hjort
Department of Mathematics, University of Oslo
Håvard Mokleiv Nygård
Peace Research Institute Oslo (PRIO)
Abstract
Have great wars become less violent over time, and is there something we might identify as the long peace?We
investigate statistical versions of such questions, by examining the number of battle-deaths in the Correlates of
War dataset, with 95 interstate wars from 1816 to 2007. Previous research has found this series of wars to be
stationary, with no apparent change over time. We develop a framework to find and assess a change-point in this
battle-deaths series. Our change-point methodology takes into consideration the power law distribution of the
data, models the full battle-deaths distribution, as opposed to focusing merely on the extreme tail, and evaluates
the uncertainty in the estimation. Using this framework, we find evidence that the series has not been as stationary
as past research has indicated. Our statistical sightings of betterangelsindicatethat1950representsthemostlikely
change-point in the battle-deaths series – the point in time where the battle-deaths distribution might have
changed for the better.
Keywords
change-point analyses, decline of war, interstate conflict, power law tails, war sizes
Introduction
Is the world becoming more peaceful? The question is
both deceptively simple and quite controversial. Authors
such as Gat (2006), Goldstein (2011) and Pinker (2011)
have argued that the world is becoming steadily more
peaceful, and a multidimensional quilt of research has
contributed pieces of layers with similar stories and con-
clusions.
1
Parts of these arguments concern wars and
armed conflicts, and there, the concept of ‘the long
peace’ (Gaddis, 1989) has gained the weight of repeated
respectful use, to signal the relatively few large interstate
wars in the period after World War II (WWII).
While the empirical pattern constituting the long
peace is not in itself disputed, some recent investigations
have questioned whether the pattern can be said to con-
stitute a statistically established trend (see e.g. Cirillo &
Taleb, 2016; Clauset, 2017, 2018; Braumoeller, 2019).
Could this long period of relative peace simply be a
random occurrence in an otherwise homogeneous war-
generating process, or does it represent a significant
change, a trend towards peace? Cirillo & Taleb (2016),
Corresponding authors:
cmlcunen@math.uio.no, nils@math.uio.no, havnyg@prio.org
1
See e.g. the collection of review articles in the 50th anniversary issue
of the Journal of Peace Research (Volume 51, Issue 1).
Journal of Peace Research
2020, Vol. 57(2) 221–234
ªThe Author(s) 2020
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DOI: 10.1177/0022343319896843
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