UCDP/PRIO Armed Conflict Dataset Codebook1

Version 4-2016

Uppsala Conflict Data Program (UCDP)
www.ucdp.uu.se

Centre for the Study of Civil Wars,
International Peace Research Institute, Oslo (PRIO)
www.prio.no/cscw

When using the data, please cite Gleditsch et al. (2002), the most recent presentation of thedata (Melander, Pettersson and Themnér), and (when appropriate) this codebook. Please
always include the version number in analyses using the dataset. When referring to thedataset, make sure to use the correct name: the UCDP/PRIO Armed Conflict Dataset.

1

The first release of the Armed Conflict Dataset was prepared at PRIO in 2002 in close collaboration withresearchers at the Department of Peace and Conflict Research at Uppsala University and the Departments ofSociology and Political Science and Geomatics at the Norwegian University of Science and Technology (NTNU).
For a description of the division of labor in creating the database, see the first footnote in Gleditsch et al. (2002:
615). This footnote also lists the financial sources of support for the entire project and credits for comments andadvice received along the way.
This is version 4-2016 of the codebook and associated documents. We are grateful to several colleagues andexternal users for constructive comments. For our policy on version labeling, see Section 2.3 below, and for acomplete history of earlier versions see the document called Version History. For further comments andsuggestions on the data and the codebook, please communicate both to project leader in Uppsala Lotta Themnér(lotta.themner@pcr.uu.se) and to jpr@prio.no.

This version compiled and updated by:
Lotta Themnér

Uppsala Conflict Data Program (UCDP)

Earlier versions and definitions:Peter Wallensteen
Birger Heldt
Margareta Sollenberg
Mikael Eriksson &Stina Högbladh

Uppsala Conflict Data Program (UCDP)
Håvard StrandHåvard M. Nygård
Halvard Buhaug
Joachim Carlsen
Nils Petter GleditschHåvard Hegre
Christin M. Ormhaug &Lars Wilhelmsen

International Peace Research Institute, Oslo (PRIO)

1 Introduction
This document describes the UCDP/PRIO Armed Conflict Dataset, a joint project between
the Uppsala Conflict Data Program (UCDP) at the Department of Peace and ConflictResearch, Uppsala University and the Centre for the Study of Civil War at the International
Peace Research Institute in Oslo (PRIO). The dataset was first presented in Gleditsch,
Wallensteen, Eriksson, Sollenberg & Strand (2002), and is available for download fromhttp://www.pcr.uu.se/research/ucdp/datasets/. The project is part of the larger Uppsala
Conflict Data Program, which is thoroughly described at www.ucdp.uu.se.
Both UCDP and PRIO offer a range of other datasets, compatible with the UCDP/PRIO
dataset. Of special importance is the UCDP Dyadic dataset which is based on the UCDP/PRIO
Armed Conflict Dataset, but goes beneath the conflict level and focuses on different dyads
within each conflict. For more information on the UCDP Dyadic dataset, and for freedownload visit UCDP’s web page. Further compatible datasets can be found on both PRIO’s
and UCDP’s web pages.
Version 4-2016 is updated in accordance to the changes listed in Melander, Pettersson and
Themnér (2016), and the 2015 conflicts have been added to the dataset. We refer the reader
to our Version History document for details of other changes and revisions to the dataset. The
dataset will continue to be updated with new data annually.

2 Definition of Conflict
The main unit in this dataset is an “Armed Conflict” as defined by UCDP.2 This definition ispresented unabridged in Section 2.1. Each conflict is listed in the database and given a unique
ID code. The temporal aspect of a conflict is not addressed by this definition; hence, two
conflict episodes over the same incompatibility will be assigned the same ID regardless of thetime separating them. See below for further clarifications.

2.1

Armed Conflict

UCDP defines conflict as: “a contested incompatibility that concerns government and/or
territory where the use of armed force between two parties, of which at least one is thegovernment of a state, results in at least 25 battle-related deaths.”
The separate elements of the definition are operationalized as follows:(1)Use of armed force: use of arms, resulting in deaths.

2For a more in-depth discussion on definitions, see http://www.pcr.uu.se/research/ucdp/definitions/.

1(1.1) Arms: any material means, e.g. manufactured weapons but also sticks, stones, fire,
water etc.
(2)25 deaths: A minimum of 25 battle-related deaths per year and per dyad (see Item 3.3 inthis definition) in an incompatibility.3(3)Party: A government of a state or any opposition organization or alliance of organizations.
UCDP distinguishes between primary and secondary parties. Primary parties are thosethat form an incompatibility by stating incompatible positions (see Item 5 in thisdefinition). At least one of the primary parties is the government of a state.
Secondary parties are states that enter a conflict with troops to actively support one of the
primary parties. The secondary party must share the position of the primary party it is
supporting in the incompatibility.
(3.1) Government: The party controlling the capital of a state.
(3.2) Opposition organization: Any non-governmental group of people having announced
a name for their group and using armed force to influence the outcome of the statedincompatibility (see Item 5 in this definition). The UCDP only deals with formallyorganized opposition. The focus is on armed conflict involving consciously
conducted and planned political campaigns rather than spontaneous violence.
(3.3) Dyad: A dyad consists of two conflicting primary parties. At least one of the primaryparties must be the government of a state. In interstate conflicts, both primaryparties are state governments.4 In intrastate and extrasystemic conflicts, the nongovernmental primary party includes one or more opposition organization(s). A
conflict can include more than one dyad. If e.g. a government is opposed by three
rebel groups over the same incompatibility, the conflict is made up of three dyads.
Note that secondary parties (i.e. intervening states supplying troops to one of the
primary parties) do not lead to the formation of additional dyads.
(4)State: A state is an internationally recognised sovereign government controlling a specificterritory or an internationally unrecognised government controlling a specified territory
whose sovereignty is not disputed by another internationally recognized sovereign
government previously controlling the same territory. See Section 4 for details on thesample of countries covered by this definition.
(5)Incompatibility concerning government or territory: The incompatibility, as stated by theparties, must concern government and/or territory.
(5.1) Incompatibility: The stated general incompatible positions.

3 Note that an incompatibility involving two opposition groups, each involved in clashes with the government resulting in

20 deaths, would not be recorded as a conflict (neither dyad reached the minimum casualty threshold), whereas anincompatibility involving a single opposition group that caused 25 battle-deaths would be included in the dataset.
4With three exceptions, the primary parties in interstate conflicts consist of only one actor on each side (and thus only
constitute one dyad). See description of Location (Section 3.2) below for further information on these cases.

2

(5.2) Incompatibility concerning government: Incompatibility concerning type of politicalsystem, the replacement of the central government, or the change of its
composition.
(5.3) Incompatibility concerning territory: Incompatibility concerning the status of aterritory, e.g. the change of the state in control of a certain territory (interstate
conflict), secession or autonomy (internal conflict).
For information on how these elements and definitions are connected to the different fields
in the dataset more precisely, see Section 3.

2.2

Missing Data Problems

The missing data code is -99. However, the dataset does not include unclear conflicts where
information on key variables to the definition of conflict is uncertain or missing. Keyvariables are those related to the incompatibility, actors and intensity. In addition, a numberof events have been identified as potentially in accordance with the criteria for inclusion.
These events include possible new dyads and additional years for active conflicts. Consult thelist of unclear cases for further information.
The information also varies with regard to the level of precision. For the start date variables,
the precision level is indicated in a separate variable, see Sections 3.15 and 3.17. Apart from
that, the dataset only includes information when we are quite confident that it is correct. The
bias produced by this approach is against the inclusion of conflicts in the earlier decades andin the less-developed world. An armed conflict in a developed country in the 1990s is more
likely to be recorded than a conflict in a less developed country in the 1950s.

2.3

Version Name Convention

This codebook corresponds to Version 4-2014 of the UCDP/PRIO dataset. For every new
release, substantial changes will be documented in a separate document. 5 This should be
helpful to researchers trying to replicate a particular study. We recommend that wheneverthis dataset is used, the version number should be cited.
The version number is a combination of a number and a year. The number is increased when
the structure of the dataset is significantly changed. The year refers to when the dataset is
updated with new observations. If there are changes in the data between yearly updates, aletter is used behind the year.

5 http://www.pcr.uu.se/research/ucdp/datasets/ucdp_prio_armed_conflict_dataset/33 The Main Conflict Table
The observation (or unit) in the Main Conflict table is the conflict-year. Each conflict is listed
in all years where fighting in one or more dyad(s) caused at least 25 battle-related deaths.
This is in contrast to Version 2.1 (and earlier versions) of the dataset.6
The calendar year is the basic unit of every observation. Thus, if a conflict during the period
June–September results in 30 casualties, that year will be recorded as a year of conflict.
However, if the same number of casualties occurred in the period November–February andthe conflict failed to reach the threshold of 25 battle-related deaths in either calendar year,
neither year will be coded as in conflict. This has a number of consequences that will be
discussed below. Start dates frequently refer to years prior to the first calendar year of aconflict, as the start of a conflict might be in a year with less than 25 fatalities. Small conflicts
might not be included. Certain observations might be based on a single event, such as theOmagh bombing in Northern Ireland in 1998, which exceeded the minimum threshold forarmed conflict.
Table 1: Definition of Variables In The Main Conflict Table
Variable
Label
Description
ID
Conflict identifier
The unique identifier of all conflicts
Location
Country name(s)The name(s) of the country/countries whose government(s) have a
primary claim to the issue in dispute.
SideA
Country name(s)Identifying the country/countries of side A in a conflict. Always thegovernment side in internal conflicts. Note that this is a primary
party to the conflict.
SideA2ndNameofstate(s) Identifying the country/countries supporting side A in the conflict.
supporting side A withtroops.
SideB
Country name(s) or
Identifying the opposition actor or country/ countries of side B in the
Opposition actor(s)conflict. In an internal conflict, this includes a military opposition
organization. Note that this is a primary party to the conflict.
SideBID
Identifier of actor on The unique identifier of the actor on side B.
side BSideB2ndNameofstate(s) Identifying the country/countries supporting side B in the conflict.
supporting side B withtroopsIncompIncompatibility
A general coding of the conflict issue

6 The previous formulation read ‘The observation (or unit) in the database is a conflict-year, a subconflict, or a subset ofeither over a period of time where no element in the definition described in Section 2 is changed. Each conflict is likely
to include several observations’. This definition of the primary unit made sense in the text lists that preceded this dataset,
where space was an important issue. The data structure was kept in order to stay compatible with previous versions. But
while this might be advantageous to old users, it has confused a number of new users. The new annual data structure
therefore replaced the old structure in Version 3.0.

4

Variable
Terr

Label
Name of territory

Year
Int

Year of observation
Intensity level

CumIntCumulative Intensity

Type

Conflict typeStartdate

RegionDateofconflict
initiation
Precision of startdate
Dateoffatalitythreshold in current
episodePrecision of startdate2
Episode Ended
Date when conflict
activity ended
Episode end precision
GW number(s) of side A
GW number(s) of states
supporting side A
GW number(s) of side B
GW number(s) of states
supporting side B
GW
number(s)oflocationsRegion of location

VersionVersion number

Startprec
Startdate2

Startprec2
EpEnd
EpEndDate
EpEndPrec
GWNoA
GWNoA2nd
GWNoB
GWNoB2nd
GWNoLoc

3.1

Description
The name of the territory over which the conflict is fought, provided
that the incompatibility is territory.
The intensity level in the dyad per calendar year. Two different
intensity levels are coded: minor armed conflicts and wars. See
Section 3.11 for definitions of the two categories.
The intensity of the conflict, taking into consideration the conflicthistory.
Four different types of conflict:extrasystemic, interstate, internal and internationalized internal. See
Section 3.13 for definitions of the four types.
The date, as precise as possible, of the first battle-related death in theconflict.
The level of precision for the initial start date.
The date, as precise as possible, when a given episode of conflict
activity reached 25 battle-related deaths in a year.
The level of precision for startdate2
Codes whether this is the last year of conflict activity in this episodeThe date, as precise as possible, when conflict activity ended.
The level of precision for episode end
GW numbers of all countries on side A, separated by semicolons.
GW numbers of all countries supporting side A with troops.
GW numbers of all countries on side B, separated by semicolons.
GW numbers of all countries supporting side B with troops.
GW numbers of all location countries, separated by semicolons.
Identifying the region of the location.
See Section 3.26 for the definition of the regions.
The current version of the dataset. See
Section 2.3.

ID

Conflict identifier. To download a conversion table containing new and old IDs, visit
http://www.prio.no/CSCW/Datasets/Armed-Conflict/UCDP-PRIO/Old-Versions/4-2006/

3.2

Location

Location is defined as the government side of a conflict, and should not be interpreted as thegeographical location of the conflict.
5 For internal and internationalized internal conflicts (see Section 3.13 for definition),
only one country name is listed. This is the country whose government or territory is
disputed. For certain conflicts, such as Kurdistan, the disputed territory is divided
between different countries. Following our definition, we have coded separate
conflicts for each country.
 For interstate conflict, both primary parties are listed in the Location field. Even if
several governments are involved in the conflict, only countries that fulfil the
inclusion criteria for primary actors are listed here. This normally means that two
countries are listed, but there are three notable exceptions: In the Arab-Israeli war of
1948–49 as well as the Suez war of 1956 and the war in Iraq in 2003, there are morethan two primary parties to the conflict.
 For extrasystemic conflicts, Location is set to be the disputed area, not the governmentof the colonial power. Since the Location field in these conflicts by default does notindicate members of the international system, it constitutes an exception from thedefinition presented in Section 2. Location is a string variable, listing the names of thecountries involved. These might be fighting together or against each other. The stringis split in two ways, hyphen (‘-‘) splits the different sides in an interstate war, andcomma (‘,’) splits different countries fighting together on the same side.

3.3

SideA

Side A is by definition always a primary party to the conflict. In internal conflicts, side A isalways the government side, it is one of the sides in interstate conflicts and the colonial state
in extrasystemic conflicts.
Side A is a string variable, and in the few cases where there are more than one primary party
on side A, these are separated by a comma (‘,’).

3.4

SideA2ndSide A Secondary lists all states that enter a conflict with troops to actively support side A inthe conflict. By definition, only independent states can be a secondary party in conflict. A
secondary party on side A shares the position in the incompatibility with Side A in theconflict. Side A Secondary does not need to meet the 25 battle-related deaths criterion to be
included in the dataset; an active troop participation is enough.
Side A Secondary is a string variable, where the different names are separated by a comma(‘,’).

3.5

SideB

Like Side A, Side B is by definition a primary party to the conflict. Side B is the oppositionside of all internal and extrasystemic conflicts and the second side in an interstate conflict.
6

Thus, side B can include both states and non-governmental opposition groups, depending on
the type of conflict. When the primary party listed on Side B is an opposition group, thecolumn lists the group name in abbreviated form. Even if the group changes its name during
the course of the conflict we record them under the same name for all years. Thus, instead ofrecording PRA (Popular Resistance Army) for Uganda 1982, we have recorded NRA(National Resistance Army) for all years (1982-86), even though the group only changed its
name from PRA to NRA in 1983. We refer to the UCDP Actor Dataset for the full name andname history of opposition groups.7
Side B is a string variable, where the different names are separated by a comma (‘,’).

3.6

SideBID

Side B ID is the unique identifier of the actor on side B in the conflict. For government actors,
the Gleditsch & Ward (2007) country codes are used. For non-state actors, the ID is takenfrom the UCDP Actor Dataset(http://www.pcr.uu.se/research/ucdp/datasets/ucdp_actor_dataset/).
IDs for the state(s) on side A, as well as on side A secondary and side B secondary are foundin GWNOA, GWNOA2nd and GWNOB2nd (see 3.18, 3.19 and 3.21).

3.7

SideB2ndSide B Secondary lists all states that enter a conflict with troops to actively support side B in
the conflict. Only states are included as Side B Secondary. Furthermore, the states listed share
the position in the incompatibility with Side B in the conflict. Side B Secondary does notneed to meet the 25 battle-related deaths criterion to be included in the dataset; active troop
participation is enough. Note that when there is more than one opposition organization listed
in an internal conflict, the dataset does not provide information on which of these groups thestate coded as Side B Secondary is supporting.
Side B Secondary is a string variable, where the different names are separated by a comma (‘,’).

3.8

Incomp

As a country can experience several simultaneous conflicts, it is essential to differentiate
between them. As described in Section 2.1, UCDP collects information on conflicts where theincompatibility, i.e. the general incompatible positions, concerns either government, territory
or both. Earlier versions of the UCDP/PRIO dataset only contained two incompatibility
categories, territory and government. Conflicts that concerned both territory and7 http://www.pcr.uu.se/research/UCDP/data_and_publications/datasets.htm

7

government were assigned to their primary incompatibility. From Version 4-2007 theincompatibility is coded in three categories:
1. Territory
2. Government
3. Government and Territory
Note that the incompatibility expressed in terms of government or a specific territory is crude
in the sense that possible underlying incompatibilities are not considered. In other words, thestated incompatibility is what the parties are (or claim to be) fighting over, but it says nothing
about why the parties are fighting.
While a state can only experience one intrastate conflict over government in a given year,that same state can simultaneously be a primary party to one or more interstate conflicts over
government and/or territory. In the case of intrastate territorial conflicts, multiple conflicts
can be recorded over different territories in a state in a given year.

3.9

Terr

If the incompatibility is territory, the disputed territory will be listed here. In case the twosides use different names for the disputed territory, the name listed is the one used by the
opposition organisation. One reason for this is that this is most often the name that thegeneral public recognises. Another reason is that there are cases where the disputed
territories do not have an official name. This is the case in e.g. conflict ID 227, a territorialconflict in north-eastern India. The rebel organisation NDFB is fighting for independence fora territory that is a part of the Assam region, and does not have an official, separate name.
Thus, we use the rebel's name for the territory: Bodoland.

3.10

Year

The year of observation.

3.11

Int

The intensity variable is coded in two categories:8
1. Minor: between 25 and 999 battle-related deaths in a given year.
2. War: at least 1,000 battle-related deaths in a given year.

In earlier versions of the UCDP/PRIO dataset, the intensity variable contained three categories: minor, intermediate
and war. The intermediate category was defined as “more than 25 battle-related deaths per year and a total conflicthistory of more than 1000 battle-related deaths, but fewer than 1000 per year.” Thus, the variable included a temporaldimension into the intensity coding. However, as many users incorrectly interpreted the variable as ordinal, it was decided
that the intermediate category should be represented by a separate dummy variable denoting cumulative intensity.
8

8

3.12

CumIntThis variable takes into account the temporal dimension of the conflict. It is a dummy
variable that codes whether the conflict since the onset has exceeded 1,000 battle-related
deaths. A conflict is coded as 0 as long as it has not over time resulted in more than 1,000
battle-related deaths. Once a conflict reaches this threshold, it is coded as 1.

3.13

Type

We define four types of conflict:
1. Extrasystemic armed conflict occurs between a state and a non-state group outside its
own territory. (In the COW project, extrasystemic war is subdivided into colonial war
and imperial war, but this distinction is not used here.) These conflicts are by definition
territorial, since the government side is fighting to retain control of a territory outside
the state system.
2. Interstate armed conflict occurs between two or more states.
3. Internal armed conflict occurs between the government of a state and one or moreinternal opposition group(s) without intervention from other states.
4. Internationalized internal armed conflict occurs between the government of a state andone or more internal opposition group(s) with intervention from other states (secondary
parties) on one or both sides.

3.14

Startdate

The date of the first battle-related death recorded in the conflict is coded as the Startdate in
the dataset. The date is set after the conflict fulfils all criteria required in the definition of anarmed conflict, except for the number of deaths. In some cases, the initial fatality occurs in ayear prior to the first year of activity. For instance, in the conflict in Ethiopia over the
territory Eritrea (conflict ID 78), the first battle-related deaths occurred in September 1961.
During the remaining months of 1961, the conflict did not reach the required 25 battlerelated deaths threshold and the conflict is thus coded as inactive in 1961. 25 battle-related
deaths were not recorded until three years later.9

9 In earlier versions of the dataset the Startdate was assigned a new value whenever there was a complete change on side

B. Departing from the new Startdate users could break a conflict up into different periods. However, with theintroduction of episodes in the UCDP/PRIO dataset (see Section 3.16) and with the launching of the new UCDP Dyadic
dataset this became redundant.

9

3.15

Startprec10

The Startdate is coded as precisely as possible. For certain conflicts we can pinpoint the startof the armed conflict down to a single event, taking place on a specific day. For otherconflicts, this is not possible, due to lack of precise information. The Startprec (start precision)is coded to highlight the level of certainty for the date set in the Startdate variable.
1. Day, month and year are precisely coded; we have good information on the event.
2. Day is assigned; month and year are precisely coded. The assigned date can either be
one of several events that can be classified as the first; it can be the last day in a period
when several fatalities have been reported jointly or it can be an event that different
sources claim occurred on different dates.
3. Day is unknown; month (or a period of 30 days, not necessarily a calendar month) andyear are precisely coded. The day is known to be in a given month or 30 day-period, but
we are missing information on an exact date. Day is then set to the last day of the period.
4. Month is assigned; year is coded precisely.
5. Day and month are unknown, year is coded precisely. Day and month are set as
precisely as possible. For example, if an event is known to have taken place sometime
between January and August, the date is coded as 31 August of the coded year, with a
precision of 5.
6. Year is assigned. There is a wide disagreement between different sources, so that noteven year can be coded precisely. The start year is assigned based on subjective
judgment. Day and month are set as the 31 December of the coded year.
7. Year is missing. No information on the start date is available; Startdate is set to 31
December of the first year recorded in the conflict.

3.16

Startdate2

With Version 4-2008 of the dataset, the coding of Startdate2 was changed. Whereas it used togive information on the first time the conflict reached 25 battle-related deaths in one
calendar year, thus indicating the date that the conflict fulfilled all criteria required in thedefinition of an armed conflict for the first time, it now gives the date, as precise as possible,
when a given episode of conflict activity reached 25 battle-related deaths. Thus, for each
episode of a conflict, a new Startdate2 is coded. In case precise information is lacking,Startdate2 is by default set to 31 December.
An episode is defined as continuous conflict activity. Consequently, a new episode is coded
whenever a conflict restarts after one or more year(s) of inactivity. The introduction of

10 Theformat for coding start dates has been slightly changed in 2014, in an attempt to provide more detailed
information.

10

episodes within conflicts enables users to distinguish between different phases in the conflict
and, potentially, code these as separate conflicts.

3.17

Startprec2

For Version 4-2014 of the dataset, the categories for this variable are similar to those ofStartprec.

3.18

EpEnd

EpEnd is a dummy variable that codes whether the conflict is inactive the following year andan episode of the conflict thus ends. If the conflict is inactive the following year(s), thisvariable is coded as 1. If not, a 0 is coded.

3.19

EpEndDate

This variable is only coded in years where EpEnd has the value 1. If a conflict year isfollowed by at least one year of conflict inactivity, the EpEndDate variable lists, as precise as
possible, the date that violence stopped.
Previously, this variable has been taken directly from UCDP’s Conflict Termination Dataset.11
However, as UCDP has proceeded in its event coding exercise (read more about this projectand its releases at http://www.ucdp.uu.se/ged/data.php#) many of the dates have been revised.
If detailed information is lacking the date is set to 31 December.

3.20

EpEndPrec

The enddate is coded as precisely as possible. For certain conflicts we can pinpoint thetermination of the armed conflict down to a single event, taking place on a specific day. For
other conflicts, this is not possible, due to lack of precise information. The Endprec (endprecision) is coded to highlight the level of certainty for the date set in the Enddate variable.
1= Day, month and year are precisely coded; we have good information on the event.
2= Day is assigned; month and year are precisely coded. The assigned date can either be oneof several events that can be classified as the last; it can be the last day in a period whenseveral fatalities have been reported jointly or it can be an event that different sources claim
occurred on different dates.

11

For a presentation of the data, see Kreutz, Joakim (2010) How and When Armed Conflicts End: Introducing the
UCDP Conflict Termination Dataset. Journal of Peace Research 47(2):243-250. The dataset can be found at
http://www.pcr.uu.se/research/ucdp/datasets/ucdp_conflict_termination_dataset/. For coding rules and more detailed
definition of these variables please see the Conflict Termination Dataset’s code book.

11

3= Day is unknown; month (or a period of 30 days, not necessarily a calendar month) andyear are precisely coded. The day is known to be in a given month or 30 day-period, but weare missing information on an exact date. Day is then set to the last day of the period.
4= Month is assigned; year is coded precisely.
5= Day and month are unknown, year is coded precisely. Day and month are set as precisely
as possible. For example, if an event is known to have taken place sometime between January
and August, the date is coded as 31 August of the coded year.
6= Year is assigned. There is a wide disagreement between different sources, so that not evenyear can be coded precisely. The end year is assigned based on subjective judgment.
7= Year is missing. No information on the end date is available; Enddate is set to 31 Decemberof the last year recorded in the conflict.
As with the EpEndDate variable (3.19), this variable was previously taken directly from
UCDP’s Conflict Termination Dataset. However, since many dates have been revised (seeabove), this variable has also seen numerous changes.

3.21

GWNoA

To facilitate analytical use of the dataset, country codes for the active state(s) on side A are
listed in this field. The country codes are taken from Gleditsch & Ward (2007). In line with
Section 3.3, in internal conflicts GWNoA lists the country code of the government; ininterstate conflicts it arbitrarily lists one of the states and in extrasystemic conflicts it lists thecode for the colonial state. This variable may contain more than one country.
GWNo A is a string variable, where the numbers are separated by a comma (‘,’).

3.22

GWNoA2nd

GWNo A Secondary lists the country codes for the states coded in Side A Secondary (Section
3.4).
GWNo A Secondary is a string variable, where the numbers are separated by a comma (‘,’).

3.23

GWNoB

GWNoB lists the country codes for states coded in Side B. GWNoB is only coded in interstate
conflicts, since that is the only time a state is active on side B. (see Section 3.5)
GWNoB is a string variable, where the numbers are separated by a comma (‘,’).

3.24

GWNoB2nd

GWNoB2nd lists the country codes for the states coded in Side B Secondary (see Section 0).
GWNoB2nd is a string variable, where the numbers are separated by a comma (‘,’).
12

3.25

GWNoLoc

This field contains the country code(s) for the state(s) listed in the Location variable. Thus, it
lists the country codes for the primary party/parties in the conflict.
GWNoLoc is a string variable, where the numbers are separated by a comma (‘,’).

3.26

RegionRegion of Location. This variable groups the various conflicts into five geographicalcategories, dependent on the location of the conflict. Table 2 summarizes these categories:
Table 2: Regions by GWNo

RegionNameStartGWNo

EndGWNo12345EuropeMiddle East
Asia
AfricaAmericas

200
630
700
400
2

395
698
990
625
165

3.27

VersionSee Section 2.3.

4 System Membership Description
The definition of a state is crucial to the UCDP/PRIO conflict list, and subsequently also forthe dyadic dataset.

State: A state is:a) an internationally recognized sovereign government controlling a specified territory,orb) an internationally unrecognized government controlling a specified territory whosesovereignty is not disputed by another internationally recognized sovereign
government previously controlling the same territory
The conflict definition, and hence also the dyad definition, is based upon participating
governmental actors of independent states, and the classification of a given conflict restsheavily upon the status of the different actors. In order to define the total population of states
we use the Gleditsch & Ward (1999) systems membership definition, which is based on the
Correlates of War project. Gleditsch & Ward include countries with a population of morethan 250,000 that have ‘a relatively autonomous administration over some territory’, and is‘considered a distinct entity by local actors or the state it is dependent on’ (Gleditsch & Ward,
1999: 398).

13

The Gleditsch & Ward definition differs from our original definition in two main ways. First,
for Gleditsch & Ward a state is considered to be a new entity if it is ‘considered a distinct
entity by local actors’ while the conflict definition only recognizes it as a new entity whenthe ‘sovereignty is not disputed by another internationally recognized sovereign government
previously controlling the same territory’. Second, the Gleditsch & Ward states all have a
population of more than 250,000 while our conflict definition does not prescribe a specificsize of the population. In a few cases, countries with less than 250,000 inhabitants experience
conflict or are active as secondary parties in a conflict. In those cases we use the Gleditsch &Ward tentative list of microstates. For example, the microstate Tonga was part of themultinational coalition fighting in Iraq in 2004.
The UCDP/PRIO dataset includes one political entity that lacks a country code (GWNoA is
set at -99) as it is excluded from both the Gleditsch & Ward system membership table and thetentative list of microstates: Hyderabad (Hyderabad vs. CPI and Hyderabad vs. India). In 1947
when England granted India independence, a cabinet memorandum declared that the
Princely States were free to decide to either join India or Pakistan before August 1947 - ordevise their own sovereign political system for self-governance. Hyderabad declared itself
independent on 15 August 1947. The state was populated by approximately 15,000,000
inhabitants. The system membership ended when Hyderabad was annexed by India in
September 1948, after Winston Churchill had proposed to the United Nations to consider it
as an independent state.
In a couple of cases, the dataset has a different sovereignty date for some countries that haveexperienced conflict:

Croatia
Gleditsch & Ward: 25 June 1991 (declares independence)
UCDP/PRIO: 27 April 1992 (the new constitution of Yugoslavia)

Georgia:
Gleditsch & Ward: 6 September 1991 (the USSR’s recognition of Georgia’s declarationof independence, on 9 April 1991)
UCDP/PRIO: 21 December 1991 (USSR formally ceased to exist)

Comment: While Gleditsch & Ward claim that the USSR recognised Georgia’s
independence on 6 September, this seems to be incorrect. On 6 September the Soviet
Union recognized the Baltic States’ independence, but not Georgia’s. Instead, theSoviet Union in early September 1991 refused to discuss recognition of the declarationof independence.
14

Gleditsch & Ward use a slightly modified version of the COW numbering system. The tablebelow presents the system membership table that we base our data tables on. These data are
based on Glelditsch & Ward’s 2013 version of the list of independent state, which is update
through 31 December 2012.

Table 3 List of System Members Since 1946

StateNum

StateAb StateName

StartYear EndYear

2
20
31
40
41
42
51
52
53
70
80
90
91
92
93
94
95
100
101
110
115
130
135
140
145
150
155
160
165
200
205
210

USA
CAN
BHM
CUB
HAI
DOM
JAM
TRI
BAR
MEX
BLZ
GUA
HON
SAL
NIC
COS
PAN
COL
VEN
GUY
SUR
ECU
PER
BRA
BOL
PAR
CHL
ARG
URU
UKG
IRE
NTH

1946
1946
1973
1946
1946
1946
1962
1962
1966
1946
1981
1946
1946
1946
1946
1946
1946
1946
1946
1966
1975
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946

United States of America
CanadaBahamasCuba
Haiti
Dominican Republic
Jamaica
Trinidad and Tobago
Barbados
MexicoBelizeGuatemalaHonduras
El Salvador
Nicaragua
Costa Rica
PanamaColombia
Venezuela
GuyanaSurinamEcuador
Peru
BrazilBoliviaParaguay
Chile
Argentina
Uruguay
United Kingdom
IrelandNetherlands

15

2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

StateNum

StateAb StateName

StartYear EndYear

211
212
220
225
230
235
260
265
290
305
310
315
316
317
325
338
339
340
341
343
344
345
346
347
349
350
352
355
359
360
365
366
367
368
369
370
371
372
373
375

BEL
LUX
FRN
SWZ
SPN
POR
GFR
GDR
POL
AUS
HUN
CZE
CZR
SLO
ITA
MLT
ALB
SER
MNG
MAC
CRO
YUG
BOS
KOS
SLV
GRC
CYP
BUL
MLD
RUM
RUS
EST
LAT
LIT
UKR
BLR
ARM
GRG
AZE
FIN

1946
1946
1946
1946
1946
1946
1949
1949
1946
1946
1946
1946
1993
1993
1946
1964
1946
2006
2006
1991
1991
1946
1992
2008
1992
1946
1960
1946
1991
1946
1946
1991
1991
1991
1991
1991
1991
1991
1991
1946

Belgium
Luxembourg
FranceSwitzerland
Spain
Portugal
German Federal Republic
German Democratic Republic
PolandAustria
Hungary
Czechoslovakia
Czech Republic
Slovakia
Italy/Sardinia
Malta
Albania
SerbiaMontenegro
Macedonia (FRY)
Croatia
Yugoslavia (Serbia)
Bosnia-Herzegovina
KosovoSlovenia
GreeceCyprusBulgaria
Moldova
Rumania
Russia (Soviet Union)
Estonia
LatviaLithuania
UkraineBelarus (Byelorussia)
Armenia
Georgia
Azerbaijan
Finland

16

2012
2012
2012
2012
2012
2012
2012
1990
2012
2012
2012
1992
2012
2012
2012
2012
2012
2012
2012
2012
2012
2006
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

StateNum

StateAb StateName

380
385
390
395
402
404
411
420
432
433
434
435
436
437
438
439
450
451
452
461
471
475
481
482
483
484
490

SWD
NOR
DEN
ICE
CAP
GNB
EQG
GAM
MLI
SEN
BEN
MAA
NIR
CDI
GUI
BFO
LBR
SIE
GHA
TOG
CAO
NIG
GAB
CEN
CHA
CON
DRC

500
501
510
511
516
517
520
522
530
531
540
541

UGA
KEN
TAZ
ZAN
BUI
RWA
SOM
DJI
ETH
ERI
ANG
MZM

StartYear EndYear

SwedenNorwayDenmark
IcelandCape Verde
Guinea-Bissau
Equatorial Guinea
GambiaMali
SenegalBenin
Mauritania
Niger
Cote D’Ivoire
GuineaBurkina Faso (Upper Volta)
Liberia
Sierra Leone
Ghana
Togo
Cameroon
Nigeria
Gabon
Central African Republic
Chad
Congo
Congo, Democratic Republic(Zaire)UgandaKenya
Tanzania/Tanganyika
ZanzibarBurundiRwandaSomalia
Djibouti
Ethiopia
EritreaAngolaMozambique

17

1946
1946
1946
1946
1975
1974
1968
1965
1960
1960
1960
1960
1960
1960
1958
1960
1946
1961
1957
1960
1960
1960
1960
1960
1960
1960
of 1960

2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

1962
1963
1961
1963
1962
1962
1960
1977
1946
1993
1975
1975

2012
2012
2012
1964
2012
2012
2012
2012
2012
2012
2012
2012

StateNum

StateAb StateName

StartYear EndYear

551
552
553
560
565
570
571
572
580
581
590
600
615
616
620
625
626
630
640
645
651
652
660
663
666
670
678
680
690
692
694
696
698
700
701
702
703
704
705
710

ZAM
ZIM
MAW
SAF
NAM
LES
BOT
SWA
MAG
COM
MAS
MOR
ALG
TUN
LIB
SUD
SSD
IRN
TUR
IRQ
EGY
SYR
LEB
JOR
ISR
SAU
YEM
YPR
KUW
BAH
QAT
UAE
OMA
AFG
TKM
TAJ
KYR
UZB
KZK
CHN

1964
1965
1964
1946
1990
1966
1966
1968
1960
1975
1968
1956
1962
1956
1951
1956
2011
1946
1946
1946
1946
1946
1946
1946
1948
1946
1946
1967
1961
1971
1971
1971
1946
1946
1991
1991
1991
1991
1991
1946

ZambiaZimbabwe (Rhodesia)
MalawiSouth Africa
Namibia
LesothoBotswana
Swaziland
Madagascar (Malagasy)
Comoros
Mauritius
MoroccoAlgeria
Tunisia
Libya
Sudan
South Sudan
Iran (Persia)
Turkey/Ottoman Empire
Iraq
Egypt
Syria
LebanonJordanIsraelSaudi Arabia
Yemen (Arab Republic of Yemen)
Yemen, People's Republic of
KuwaitBahrain
Qatar
United Arab Emirates
Oman
Afghanistan
Turkmenistan
Tajikistan
Kyrgyz Republic
Uzbekistan
Kazakhstan
China

18

2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
1990
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

StateNum

StateAb StateName

StartYear EndYear

711
712
713
731
732
740
750
760
770
771
775
780
781
790
800
811
812
816
817
820
830
835
840
850
860
900
910
920
940
950

TBT
MON
TAW
PRK
ROK
JPN
IND
BHU
PAK
BNG
MYA
SRI
MAD
NEP
THI
CAM
LAO
DRV
RVN
MAL
SIN
BRU
PHI
INS
ETM
AUL
PNG
NEW
SOL
FJI

1946
1946
1949
1948
1948
1946
1947
1949
1947
1971
1948
1948
1965
1946
1946
1953
1954
1954
1954
1957
1965
1984
1946
1946
2002
1946
1975
1946
1978
1970

Tibet
Mongolia
Taiwan
North Korea
South Korea
Japan
India
BhutanPakistan
Bangladesh
Myanmar (Burma)
Sri Lanka
Maldives
Nepal
ThailandCambodia (Kampuchea)
Laos
Vietnam, Democratic Republic ofVietnam, Republic of
Malaysia
Singapore
Brunei
Philippines
Indonesia
East Timor
Australia
Papua New Guinea
New Zealand
Solomon Islands
Fiji

1950
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
1975
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

5 References
Gleditsch, Kristian S. & Michael D. Ward (1999) Interstate System Membership: A Revised
List of the Independent States since 1816. International Interactions 25: 393–413.
Gleditsch, Nils Petter; Peter Wallensteen, Mikael Eriksson, Margareta Sollenberg & Håvard
Strand (2002) Armed Conflict 1946–2001: A New Dataset. Journal of Peace Research
39(5): 615–637.

19

Gleditsch, Kristian S. Skrede & Michael D. Ward (2013) System membership case description
list.
Held, Birger (1993) Armed Conflicts over Government and Territory 1989–91 in Heldt,
Birger, Armed Conflict 1990–91. Uppsala: Uppsala University.
Kreutz, Joakim (2010) How and When Armed Conflicts End: Introducing the UCDP Conflict
Termination Dataset. Journal of Peace Research 47(2):243-250.
Themnér, Lotta & Peter Wallensteen (2014) Armed Conflict, 1946-2013 Journal of Peace
Research 51(4).

20