Institutional Variance of the Democratic Peace, 1816-2002: Electoral, Executive, and Federal Systems in Time and Space

The document is a codebook for a dataset tracking three dimensions of governmental institutions from 1816 to 2002: electoral systems (Majority-Plurality, Semi-proportional, Proportional Representation), executive forms (Presidential, Semi-presidential, Parliamentary, Military, Non-elective), and federalism (Unitary, Semi-federal, Federal). It defines the criteria for state inclusion based on Gleditsch and Ward (1999), requiring autonomous administration, recognition as a distinct entity, and a population over 250,000. The document details the methodology for classifying these systems, including the use of the Polity4 index to identify democracies (score >= 3) and the extrapolation of data to fill gaps during World Wars. A comprehensive coding scheme is provided for numerous countries, listing their institutional transitions over the specified period.

• The dataset classifies electoral systems into three primary groups: Majority-Plurality (using single-member districts), Semi-Proportional (falling between proportionality and majoritarianism), and Proportional Representation (representation based on the overall share of the national vote).
• Executive systems are categorized into five types: Presidential (president exercises primary influence), Semi-Presidential (prime minister as head of government and president as head of state), Parliamentary (executive depends on legislative approval), Military (direct rule by military or military-controlled civilian government), and Non-elective (non-elective selection of the effective executive, such as theocracies or 19th-century monarchies).
• The degree of federalism is classified into three categories: Unitary (sovereignty centered at the national government), Semi-Federal (elective regional legislatures exist but sovereignty remains national), and Federal (elective regional legislatures with constitutional recognition of subnational authority).
• To ensure data continuity, the author used an extrapolation technique to fill missing information during the World Wars and to extend the dataset to 2002, provided the Polity4 index score changed by less than 3 during the period.
• The criteria for including a polity in the dataset require it to have a population greater than 250,000, a relatively autonomous administration over some territory, and be considered a distinct entity by local actors or the state it depends on.

APA

Peace Research Institute Oslo (n.d.). Institutional Variance of the Democratic Peace, 1816-2002: Electoral, Executive, and Federal Systems in Time and Space. https://cdn.cloud.prio.org/files/37164f19-61ef-4179-8b18-25a75e936ab9/Institutional Variance Codebook.pdf?inline=true

Chicago

Peace Research Institute Oslo. Institutional Variance of the Democratic Peace, 1816-2002: Electoral, Executive, and Federal Systems in Time and Space. n.d. https://cdn.cloud.prio.org/files/37164f19-61ef-4179-8b18-25a75e936ab9/Institutional Variance Codebook.pdf?inline=true.

Wikipedia

{{cite report |author=Peace Research Institute Oslo |title=Institutional Variance of the Democratic Peace, 1816-2002: Electoral, Executive, and Federal Systems in Time and Space |url=https://cdn.cloud.prio.org/files/37164f19-61ef-4179-8b18-25a75e936ab9/Institutional Variance Codebook.pdf?inline=true |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{peaceresearchinstituteoslondinstitutional, author = {{Peace Research Institute Oslo}}, title = {{Institutional Variance of the Democratic Peace, 1816-2002: Electoral, Executive, and Federal Systems in Time and Space}}, institution = {Peace Research Institute Oslo}, url = {https://cdn.cloud.prio.org/files/37164f19-61ef-4179-8b18-25a75e936ab9/Institutional Variance Codebook.pdf?inline=true}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }