• Updated System Membership Data (v2008.1) Available
  We have updated the data on system membership; the data set now runs from 1816 through June 2008 (under the "Data Sets" page). (posted June 25, 2008)

• Trade Data (v2.0) Available
  A new and expanded version of the COW trade data (version 2.0) has been completed, and is available under the "Data Sets" page. This version of the data covers the period 1870-2006 period. (posted June 23, 2008)

• Updated Direct Contiguity Data (v3.1) Available
  We have updated the data on direct contiguity from 1816-2006 (under the "Data Sets" page). This version makes minor corrections, adds contiguity relationships for new states, and provides additional notes about all contiguity relationships in the data. (posted October 2, 2007)

• Updated Militarized Dispute Data (v3.1) Available
  We have updated the data on militarized disputes (MIDA, MIDB, MIDI, MIDIP, and Dyadic MIDs) from 1816-2001 (under the "Data Sets" page). This update corrects codings for several MIDs after an investigation of accumulated error reports. (posted September 26, 2007)

• Annotated War Bibliography Available
  Zachary Shirkey and Alex Weisiger have prepared an annotated bibliography for some of the lesser-known COW wars. The bibliography is available under the Interstate War Dataset page (under the "Data Sets" page). (posted September 26, 2007)

• Diplomatic Exchange Data (v2006.1) Documentation Updated
  We have updated the documentation on diplomatic exchanges between states from 1817-2005 (under the "Data Sets" page) to clarify differences in how the data are constructed from 1985 forward (due to changes in source information). (posted May 21, 2007)

• Diplomatic Exchange Data (v2006.1) Available
  Data on diplomatic exchanges between states from 1817-2005 are now available under the "Data Sets" page. (posted 12/4/2006)

• Updated Capabilities Data (v3.02) Available
  v3.02 of the national capabilities data set has been released and is now available under the "Data Sets" page. This update corrects a few errant values for Singapore, and fills in data for 4 small Pacific states from 1999-2001. (posted 6/6/2005)

• Updated System Membership Data (v2004.1) Available
  v2004.1 of the system membership data set has been released and is now available under the "Data Sets" page. This update brings the system membership list through 2004. (posted 2/2/2005)

• New Director; Project Name Change
  Paul Diehl has been named the new director of the Correlates of War project. In addition, the name of the Correlates of War 2 project has been changed (back!) to the Correlates of War project. (posted 1/11/2005)

• Updated Documentation and Subcomponent Data Sets for National Material Capabilities Data (v3.01) Available
  A substantially revised and updated version of the national capabilities documentation has been released, along with databases containing additional detail concerning the individual subcomponents of the capabilities data, including sources for individual data points and data quality codes. These are available under the National Material Capabilities section of the "Data Sets" page. (posted 7/2/2004)

• Updated National Material Capabilities Data (v3.01) Available
  v3.01 of the national capabilities data set has been released and is now available under the "Data Sets" page. This update corrects one important error in the military personnel data for Russia in 2000. (posted 3/26/2004)

• MID Narratives Available
  Summary information about many MIDs is now available in the form of "narratives" about the MIDs under the MID data section of the "Data Sets" page. The narratives give a prose description of the actors, issues, and some critical actions occuring within each MID. (posted 3/26/2004)

• IGO Data v2.1 Available
  An updated version (v2.1) of the data on state membership in intergovernmental organizations from 1815-2000 are now available under the "Data Sets" page. (posted 12/23/2003)

• IGO Data v2.0 Available
  Data on state membership in intergovernmental organizations from 1815-2000 are now available under the "Data Sets" page. (posted 11/19/2003)

• Colonial / Dependency Contiguity Data v3.0 Available
  Data on contiguity relationships involving state colonies and dependencies from 1816-2002 are now available under the "Data Sets" page. (posted 10/31/2003)

• National Material Capabilities Data v3.0 Available
  An update to the national capabilities data set has been completed, and the data set is now available under the "Data Sets" page. The new capabilities set covers the 1816-2001 period, and includes 6 individual capability components and the CINC score derived from them. Along with extending the data to 2001, we have recollected/recomputed some series from scratch for this release. (posted 10/9/2003)

• MID Data v3.02 Available; includes dyadic and incident-level data
  Version 3.02 includes information about the specific component incidents that occurred within each MID for the 1993-2001 period (along with the MIDs ongoing at the end of 1992). In addition, version 3.02 includes a dyadic version of these disputes which codes only actual militarized interactions between all MID participants. Minor corrections have also been made to the data, including several corrections to the pre-1992 data. The data and a full description of the changes are available under the Militarized Interstate Dispute data section of the "Data Sets" page. (posted 10/9/2003) Note: A typo was discovered in the MIDA file on 10/14/2003, and has been updated with the release of v3.021 of this file. (posted 10/14/2003)

• Alliance Data v3.03 Available
  Minor corrections have been made to the alliance v3 data set (correcting 1 typo and 3 differences between the alliance set and the COW state membership list), resulting in a new version. The data and a full description of the changes are available under the alliance data section of the "Data Sets" page. (posted 7/3/2003)

• Militarized Interstate Dispute Data v3.0 Available
  Following a 3-year, multi-university research project supported by the National Science Foundation, a new and expanded version of the COW Militarized Dispute Data (version 3.0) has been completed, and is available under the "Data Sets" page. This expanded version of the MID data covers the 1816-2001 period. (posted 4/21/2003)

• State System Membership v2002.1 Available
  A newly updated version of the COW interstate system membership data (version 2002.1) has been completed, and is available under the "Data Sets" page. This expanded system membership list covers the 1816-2002 period. (posted 4/21/2003)

• Dyadic Alliance Data v3.02 Available
  v3.02 of the dyadic alliance data (single-observation-per-year data only) corrects a programming error which led to a handful of dyad-year observations (approximately 40 out of 88,000+ dyad-years) being dropped in v3.01. The new version and a full description of the change are available under the alliance data section of the "Data Sets" page. (posted 3/14/2003)

• Alliance Data FAQ Available
  A "Frequently Asked Questions" list about the alliance v3 data set, and specific codings within in it, is now available on the alliance data page under the "Data Sets" page. (posted 3/12/2003)

• Alliance Data v3.01 Available
  We have changed the format of one variable in the alliance v3.0 data set, resulting in a new version. We have modified the state names in the alliance data set to remove all commas (and so, e.g., “Korea, South” is now listed in the data set as “South Korea”). NO SUBSTANTIVE CHANGES TO THE ACTUAL CORE DATA HAVE BEEN MADE IN THIS RELEASE (in alliance numbers, alliance types, state membership in alliances, or dates of alliance entry/exit). If you have been using v3.0 data without a problem, there is no need to download v3.01 and perform new analysis. The data in the new format is available under the alliance data section of the "Data Sets" page. (posted 2/19/2003)

• Alliance Data v3.0 Available in Dyadic Format
  The new COW alliance data (version 3.0) has been converted into two dyadic formats suitable for easy merging with dyad-year data sets. The data in the new format is available under the alliance data section of the "Data Sets" page. (posted 1/6/2003)

• Alliance Data v3.0 Available
  A new and expanded version of the COW alliance data (version 3.0) has been completed, and is available under the "Data Sets" page. This expanded version of the alliance data covers the 1816-2000 period. (posted 12/20/2002)

• Territorial Change Dataset Update to 2000
  An update of the territorial change dataset to 2000 has been completed, and is available under the "Data Sets" page. (posted 12/20/2002)

• New Web Site
  The COW 2 web site has been redesigned and updated. All links should now be connected, and the reported status of datasets is current. Please provide us with any feedback on the new site, or notes about errors or problems, under the "Contact Us" page of the site. (posted 12/20/2002)

• In Memorium: Stuart A. Bremer.
  Stuart A. Bremer, director of the Correlates of War 2 project, passed away on October 15, 2002. Under his leadership, the Correlates of War project moved from the University of Michigan to The Pennsylvania State University in March 2001. Projects begun under his leadership will be coming to fruition over the next months and years. His leadership, energy, and attention to detail in developing high quality and well-documented data sets will be missed. (posted 11/16/2002)

• Governance Changes.
  The advisory board of the Correlates of War 2 project has ratified changes to the leadership and governance of the Correlates of War 2 project. Details on the new have been posted on the "Governance" page of this site. (posted 11/16/2002)

• New Version of Direct Contiguity Data Available Now
  Version 3.0 of the direct contiguity data, which covers the period 1816-2000, has been reviewed and is available for use now. It may be accessed and downloaded through the Data Sets tab on the COW² main page within the Geographical Proximity section. Douglas M. Stinnett, Jaroslav Tir, Philip Schafer, Paul F. Diehl, and Charles Gochman all contributed to this update and extension of the data set, and they are to be thanked for their efforts. (posted 2/6/02)
  
• New Version of  Energy Consumption Data Available Soon
  Version 3.0 of the primary energy consumption data set is undergoing it's final checks and will be distributed soon. This data set covers the period 1816-1997 and includes data for more country-years than the previous version. In addition, the source, derivation procedure, and quality of each data point is specified in the data set. Chris Housenick at Penn State has conducted this update and revision, and he is preparing the appropriate documentation. Look for an announcement here in the near future. (posted 8/31/01)
  
• Alliance Update Undergoing Final Checks
  A new and expanded version of the COW alliance data (version 3.0) developed by Meredith Sarkees (DePaul University) and Douglas Gibler (University of Kentucky) has been received at the project and is undergoing final checks. This set will cover the 1816-2000 span and include more precise dates of the beginning and end of alliances than previous versions. (posted 8/31/01)
  
• Updated Direct Contiguity Data Coming Soon
  An updated version of the direct (state-to-state) contiguity data covering the period 1816-2000 has been prepared by Paul Diehl and Doug Stinnett at the University of Illinois. The required review process has begun at Penn State, and we hope to be able to release the data quite soon (i.e, this fall). (posted 8/31/01)
  
• COW² Fall Meeting Schedule
  The fall meeting schedule at Penn State has been set, and those who find themselves in the vicinity of State College on a meeting day should feel free to attend. (posted 8/26/01)
  
• Report on The Study of Future War and the Future Study of War Workshop, March 16-18, 2001
  About forty people attended the successful workshop, and a brief report on the meeting is available here. The principal papers from this meeting will appear in a forthcoming issue of Conflict Management and Peace Science.
  
• New Versions of War Data Available
  Versions 3.0 of the inter-, extra-, and intra-state war data are now available on the COW² web site. These data sets update the COW war data through 1997, and more can be learned about these in the Data Sets section of the web site. A revision and extension of these data sets to the year 2000 is in preparation.
  
• Workshop on The Study of Future War and the Future Study of War, March 16-18, 2001
  To officially recognize the transfer of the Correlates of War project from the University of Michigan to the Pennsylvania State University, a workshop is being held at Penn State's University Park campus. Featured guest speakers at the meeting will be J. David Singer, James Lee Ray, Paul Diehl, Brian Pollins, and Paul Hensel. Details are available here .
  

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