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 Dataset, 2002–2010: Procedures, Coding Rules and Description." Conflict Management and Peace Science 32: 222-42.

Dyadic Data Set Bibliography Entry:                                                                      

Zeev Maoz, Paul L. Johnson, Jasper Kaplan, Fiona Ogunkoya, and Aaron Shreve 2018. The Dyadic Militarized Interstate Disputes (MIDs) Dataset Version 3.0: Logic, Characteristics, and Comparisons to Alternative Datasets, Journal of Conflict Resolution, DOI: http://journals.sagepub.com/doi/full/10.1177/0022002718784158.

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 gpalmer@psu.edu.


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.


The MID 4.2 dataset reflects changes that were inserted following re-evaluation of the entire dataset, following comments and suggestions by users. We are especially indebted to Douglas Gibler, Erin Little, Steven Miller, and faculty and students from Penn State University, the University of Alabama, and the University of California, Davis for their work on the MID data cleaning over the period of 2014-2018. A slightly revised version (MID 4.2.1) will be published shortly which will reconcile differences between the MID(A), MID(B), and the dyadic MID dataset.


Data Set 

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_4.2.csv: Data on MIDs from 1816-2010, at the dispute level. Contains one record per militarized dispute.

3. MIDB_4.2.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_4.2.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_4.2.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 v. 3.1 and documentation:

The dyadic MID 3.1 dataset covers the period of 1816-2010. It combines work of the Dyadic MID dataset developed by Zeev Maoz (Dyadic MID 2.1) and the dyadic MID dataset developed by the Penn State University team (MID(I)). The current version DyadMID 3.1 contains a major cleaning and re-evaluation of the entire dataset, reconciliation of the dyadic MID and the other MID datasets, and reconciliation of the MID and interstate war datasets. A new version (Dyadic MID 3.2) is in preparation completing the reconciliation process and containing new variables. It will be released by the end of 2018. Funding for the dyadic MID dataset was provided by a Minerva Grant #W911NF-15-1- 0502 of the Army Research Office, the United States Department of Defense.

There are three files in the dyadic MID ZIP file: 

1. Dyadic MIDs 3.1.csv: A comma-separated file (does not include variable labels and value labels)

2. Dyadic MID 3.1.dta: A Stata dataset of the dyadic MIDs (includes variable and value lables)

3. Dyadic MID 3.0.pdf: A codebook of the dyadic MID dataset.

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.