Militarized Interstate Disputes (v4.1)
Version 4 of the Militarized Interstate Dispute (MID) data collection compiled by the Correlates of War Project provides information about conflicts in which one or more states threaten, display, or use force against one or more other states between 1816 and 2010. By definition, “Militarized interstate disputes are united historical cases of conflict in which the threat, display or use of military force short of war by one member state is explicitly directed towards the government, official representatives, official forces, property, or territory of another state. Disputes are composed of incidents that range in intensity from threats to use force to actual combat short of war” (Jones et al. 1996: 163).
Version 3.10 of the MID data set covered the 1816-2001 period. The data collection project that culminated in version 4.0 gathered new data on all MIDs that began between 2002 and 2010, along with those MIDs that began before 2002 but were still ongoing on December 31, 2001. Version 4 also updates the earlier data set with corrections made after an investigation of cases where errors or discrepancies had been reported to the COW project between 2007 and 2013. The version 4 MID data should be considered to supersede other MID data sets.
In any papers or publications that utilize this data set, users are asked to give the version number and cite the article of record for the data set, as follows:
Main Bibliography Entry:
Palmer, Glenn, Vito D'Orazio, Michael Kenwick, and Matthew Lane. 2015. "The MID4 Data Set: Procedures, Coding Rules, and Description." Conflict Management and Peace Science. Forthcoming.
Dyadic Data Set Bibliography Entry:
Ghosn, Faten, and Scott Bennett. 2003. Codebook for the Dyadic Militarized Interstate Incident Data, Version 3.10. Online: http://correlatesofwar.org.
MID 3 Bibliography Entry:
Ghosn, Faten, Glenn Palmer, and Stuart Bremer. 2004. "The MID3 Data Set, 1993–2001: Procedures, Coding Rules, and Description." Conflict Management and Peace Science 21:133-154.
MID 2.1 codebook/citation: The codebook for the MID data version 3.0 builds on the documentation for the MID version 2.1 data set:
Jones, Daniel M., Stuart A. Bremer and J. David Singer. 1996 ."Militarized Interstate Disputes, 1816-1992: Rationale, Coding Rules, and Empirical Patterns." Conflict Management and Peace Science 15:163-213.
Questions and Feedback
The MID data are hosted by Glenn Palmer, Penn State, under the COW Data Set Hosting Program. In case of questions or concerns concerning the data or coding rules, he may be contacted by email at firstname.lastname@example.org.
MID 4 Project Development
The latest iteration of the Correlates of War Project's Militarized Interstate Dispute Data (MID 4) covers the period 2002-2010, adding to the MID data gathered for the period 1816-2001. MID 4.0 was developed largely at the Pennsylvania State University under the direction of Glenn Palmer and with the assistance of two grants from the National Science Foundation (SES-0719634 and SES-0924240). Financial and research support from the Department of Political Science at Penn State University was provided and aided the project significantly. Phil Schrodt, Scott Bennett (Penn State) and Paul Diehl (Illinois) were instrumental in the development and completion of the project. Colleagues at Rice University and the University of Alabama, directed by Richard Stoll and Doug Gibler, respectively, provided timely and valued assistance.
An article of record for the MID 4 Data is in preparation as of January, 2014. We will be announcing the specifics of that article shortly.
A re-evaluation of the MID data for the years 1816-2001 is currently (January, 2014) in progress. We anticipate that a number of disputes and incidents will be altered in some form or removed from the data completely. We will release the revised data, explaining the changes made, as soon as possible.
The files associated with the MID 4 data set can be obtained below in ZIP files. All data files are in .csv (comma-delimited) format. In this format, values are separated by commas, with string values (e.g. state names) in quotations. The first line of each data file is a header record containing the variable names. The codebooks and narratives are in .pdf format.
MID-level data and documents
There are five files in the MID-level ZIP file:
1.MID_v4.0_Codebook.pdf: Main codebook for the MID 4.0 data set, describing file formats and listing variables contained in the MIDA and MIDB data files.
2. MIDA_4.01.csv: Data on MIDs from 1816-2010, at the dispute level. Contains one record per militarized dispute.
3. MIDB_4.01.csv: Data on MIDs from 1816-2010, at the participant level. Contains one record per militarized dispute participant.
4. MID_Narratives_1993-2001.pdf: Narratives for 1993-2001 MIDs containing a brief prose summary of key actors and actions.
5. MID_Narratives_2002-2010.pdf: Narratives for 2002-2010 MIDs containing a brief prose summary of key actors and actions.
Incident-level data and documents
There are three files in the incident-level ZIP file:
1. MII_v4.0_Codebook.pdf: Main codebook for the MID 4.0 incident data sets, describing file formats and listing variables contained in the MIDI and MIDIP data files.
2. MIDI_4.01.csv: Data on incidents within MIDs from 1993-2010 (along with disputes ongoing as of 12/31/1992), at the incident level. Contains one record per militarized incident.
3. MIDIP_4.01.csv: Data on incidents within MIDs from 1993-2010 (along with disputes ongoing as of 12/31/1992), at the incident-participant level. Contains one record per participant in each incident.
Dyadic MID data and documentation (MID 3.1 only; MID 4 coming soon):
There are two files in the dyadic MID ZIP file:
1. Codebook for Dyadic MID Data v3.10.pdf: Main codebook for the dyadic version of the MID 3 data set, describing coding procedures and the dyadic file format, and listing variables.
2. MIDDyadic_3.10.csv: Data on dyadic MIDs from 1993-2001 (along with disputes ongoing as of 12/31/1992), at the dyad level. Contains one record per dyadic MID.
Documents discussing data changes:
There are four files in the data changes ZIP file:
1. MID_Changes_as_of_v4.0.pdf: Document discussing changes made to MID data between MID v3.10 and v4.0.
2. MID_v3.0.associated document.pdf: Auxiliary information presented during release of the MID 3.0 data set, including discussion of new and changed variables relative to MID 2.1, updates, and a discussion of particular case codings in MID 3.0.
3. Discussion - MID changes as of v3.10.pdf: Document discussing changes made to MID data since v3.02.
4. Discussion - MIDs reviewed and unchanged as of v3.10.pdf: Document discussing changes/questions examined, but where changes were not needed.
MID-level.zip — Zip archive, 962 kB (985930 bytes)
Incident-level.zip — Zip archive, 179 kB (183852 bytes)
Dyadic-MID.zip — Zip archive, 36 kB (37087 bytes)
data-changes.zip — Zip archive, 82 kB (84504 bytes)
Source data include the citations to the original materials used to code each dispute or incident. All data files are in .csv (comma-delimited) format. In this format, values are separated by commas, with string values (e.g. state names) in quotations. The first line of each data file is a header record containing the variable names.
Source Data for MID 4
1. MID v4.0_GeneralSources.pdf: List of the sources used in coding the MID 4.0 data set.
Source Data for MID 3.0
The source data used to code the MID 3.0 data set can be obtained in one ZIP file containing the following:
1. MID 3.0 SourceData Codebook.pdf: Main codebook for the sources used in MID 3.0 data set, listing variables.
2. MID 3.0 Standard Source Abbreviations.pdf: Main codebook for the sources used in MID 3.0 data set, listing variables.
3. MID3.0_Sources.csv: Data on sources used to code incidents in MIDs from 1993-2001. The number of records per incident corresponds the number of sources used to code any given incident.
4. MID3.0_Sources.xls: Data on sources used to code incidents in MIDs from 1993-2001. The number of records per incident corresponds the number of sources used to code any given incident.
Source Data for MID 2.1
The source data used to code the MID 2.1 data set can be obtained in one ZIP file containing the following:
1. MID 2.1 SourceData Codebook.pdf: Main codebook for the sources used in MID 2.1 data set, providing historical overview of the project and listing variables.
2. MID2.1_SpecificSources.csv: Data on sources used to code incidents in MIDs prior to 1993. The number of records per MID corresponds the number of sources used to code any given dispute.
3. MID2.1_GeneralSources.csv: Data on sources used to code MIDs prior to 1993. The file contains the full names for sources which are abbreviated in the source data file, and sources contained in the COW MID bibliography that do not correspond to specific MID numbers.
MID_v4.0_GeneralSources.pdf — PDF document, 5 kB (5652 bytes)
MID3_Sources.zip — Zip archive, 352 kB (361370 bytes)
MID2.1_Sources.zip — Zip archive, 174 kB (178883 bytes)
MID 4.01 released
MID 4.01 was posted on Feb. 5, 2013. This release corrected minor errors and discrepancies with the originally-posted v4.0 data. The following changes were made:
1. Fixed Dispute and Incident numbering issues in several cases.
2. Corrected COW country codes for actors in four cases.
3. Changed the start year of one case.
4. Changed the Dispute and Incident Hostility Level to match the Highest Action in seven cases.
5. Changed the Highest Dispute Action to match the Highest Incident Action in several cases.
MID 4.0 released
MID 4.0 was released January, 2013, including some changes to MID 3. (See the source data for MID 4)
Data Updates for MID 3.10
On September 26, 2007, the MID data were updated to version 3.10. Updating for version 3.10 focused on the following issues:
Since the release of v3.02, the COW project has investigated error reports, questions, and reports of discrepancies on nearly 150 particular MIDs submitted by numerous scholars, including Zeev Maoz, Patrick Regan, Russell Leng, Ashley Leeds, Mark Souva, and others. Each report has been investigated, and v3.10 has made changes/corrections to 74 different MIDs (the remaining MIDs did not require changes; error reports typically resulted from a misinterpretation of coding rules). There have been changes to a total of 100 MIDs since the release of MID 3.0. You may review a detailed cumulative list of these questions and changes that resulted and detailed listing of questions examined where it was determined that no changes in the data were required is in the MID 3 sources file.
2. Dyadic MIDs: The COW dyadic MID set (1993-2001) breaks down overall MIDs, some of which have many participants, into actual disputing pairs of states. Each dyadic MID has exactly two states involved on opposite sides; each was directly involved in militarized incidents against the other. The data set omits dyads where the two states were on opposite sides of a multi-party dispute, but never took action towards one another. While there are approximately 300 MIDs from 1993-2001, there are over 500 dyadic MIDs during this period. Version 3.10 corrects errors in the dyadic data set. These errors most often resulted from errors in the underlying (non-dyadic) MID data sets that carried over to the dyadic MID set. Other corrections and additions to the data include the following. 1) Dyadic MIDs and the related dates were not being correctly computed for states exiting and reentering a MID; in such circumstances, a new dyadic MID is now correctly coded. 2) The data now include a "dyadic MID number" as well as the base MID number; this number separates each pair of disputing states, and separates incidents of repeated involvement. 3) Hostility levels were not always reported correctly in the dyadic MID data set in the case of war. It is sometimes the case that a MID has a hostility level of "5" (war) even though no single incident reaches hostility level 5. This is because multiple instances of a use of force (hostility level "4") can accumulate to a level of war. These cases were not always picked up in the MID 3.02 data; they have been corrected with hostility levels in such cases being taken from the MIDB data set rather than the MID IP (incident) data. 4) The end dates of dyadic MID were in some cases not being correctly computed; the end date of the last incident between two states in a MID is not automatically the correct end date of the dyadic MID, as MIDs can end days or weeks after the end of the last incident. These dates have been corrected.
Incident Level Data and Dyadic Data Updates for MID v.3.02
On October 10, 2003, we replaced version 3.01 of the MID data with version 3.02. The data sets for version 3.02 include the following:
1.Incident and Incident Participant level data files: Incidents are the building blocks of MIDs, and represent individual militarized actions incidents (specific threats, displays, or uses of force) that comprise the disputes. MIDs may consist of one or many specific incidents. The MID 3.0 incident data collection reports information on each of the militarized incidents occurring with MIDs (incidents may be either escalatory or de-escalatory). MID-I contains the essential elements of each militarized interstate incident from 1993-/2001 (incidents that belonged to disputes that began in 1992 and continued into 1993 were also collected). MID-IP describes the participants in each of those incidents.
2. Dyadic MIDs: The COW dyadic MID set from 1993-2001 breaks down overall MIDs, some of which have many participants, into actual disputing pairs of states. Each dyadic MID has exactly two states involved on opposite sides; each was directly involved in militarized incidents against the other. The data set omits dyads where the two states were on opposite sides of a multi-party dispute, but never took action towards one another. While there are approximately 300 MIDs from 1993-2001, there are over 500 dyadic MIDs during this period.
3. Minor Corrections: We have made a few minor changes to data on the MIDs that were newly collected between 1992 and 2003. You may review a summary of these changes the MID 3 sources file.
4. Revisiting older MIDs: In response to various comments and questions about MID codings from the v2.1 data set, we have revisited a number of pre-1992 MIDs and made 25 corrections/changes/additions. You may review a detailed list of these questions and resulting changes and a detailed listing of questions considered which did not necessitate changes the MID 3 sources file.
5. Because the new data version include numerous documentation files, we have released all documentation files in .pdf format only. Users wishing to cut and paste from these documents can still do so using the "t" keystroke command within Adobe.
6. A typo was discovered in the MIDA_3.02.csv data file on October 14, 2003 (the MID number for MID 21 was mistakenly listed as a 20, so it appeared that MID 20 was listed twice and MID 21 not at all). The MID number for MID 21 has been corrected in MIDA_3.021.csv, which replaces MIDA_3.02.csv. No other data files were affected by the typo.
MIDB Dataset Updates (v.3.01)
On March 23, 2003, we replaced version 3.00 of the MID data with version 3.01.
1. The data in the MIDA file (main MID listing) is identical from version 3.00 to version 3.01. However, we found an erroneous case in version 3.00 of the MIDB file, and have deleted this case in version 3.01 (it should not have been in there in the first place). The case was MIDB data set dispute number 4241. This is the only change from version 3.00 to version 3.01.
2.With this release, we have also made available text file versions of the documentation as .rtf files, along with .pdf files.
Dyadic MID data is only available from the Correlates of War project from 1993-2001, because incident data (showing direct dyadic interaction) has only been systematically coded since 1993. For the pre-1993 period, either assumptions must be made in coding dyadic interaction (critically, that all states on opposite sides interacted), or additional research must be performed to identify actual interactions. In addition, coding to a dyadic form must carefully check dates of state involvement to verify that states were opponents at the same time.
MID v.2.1 (running from 1816-1992):
1. MID 2.1.zip: The .zip file contains main codebook in .txt format and three data files in .txt format.
MID v.2.1EE- provides information on a subset of escalatory incidents in 1816-1992:
1. MID 2.1 EE.zip: The .zip file contains main codebook in .pdf format and the data file in .csv format.
MIDS_210.zip — Zip archive, 87 kB (89230 bytes)