Comparative Political Data Sets

Research project

The Comparative Political Data Sets (CPDS for short) are three separate datasets compiled by researchers at the University of Berne. The three datasets contain a collection of political and institutional data, but cover different countries and time periods. The dataset called CPDS I (Armingeon et al. 2011) covers the OECD countries for the period 1960-2009 and was assembled as part of the research projects Die Handlungsspielräume des Nationalstaates and Critical Junctures: An International Comparison. The second dataset, CPDS II (Armingeon and Careja 2008), covers 28 post-communist countries for the 1989-2008 period, and was compiled as part of the research project Forms of Government: A Comparative Data Set for 28 Eastern Countries. The third dataset, CPDS III (Armingeon et al. 2011), covers 35 OECD and/or EU member countries for the 1990-2006 period. The data in this dataset are mainly drawn from the other two, but it differs from them in some respects.


  1. Comparative Political Data Set I
  2. Comparative Political Data Set II
  3. Comparative Political Data Set III

Comparative Political Data Set III


Comparative Political Data Sets






35 countries

Last reviewed


Data types and sources

Political variables based on expert coding and election data. Fiscal and social policy variables based on government statistics (national accounts).

Data download

Comparative Political Data Set III


The core of the dataset is composed of variables related to the political system and electoral rules. The dataset consists of many of the same variables as CPDS I and CPDS II, but the operationalisation is different in some cases. The variables in CPDS III are organised in thematic groups groups:

  1. Governments. Variables describing the party composition of government, changes in government and type of government (minority/majority, coalition/single party).
  2. Elections. Date of election, voter turnout, various parties’ share of votes and various parties’ share of seats.
  3. Women in parliament. Percentage of women in parliament.
  4. Party system. Various indices measuring the degree of disproportionality in the electoral system and the effective number of parties (Rae, Laakso-Taagepera, Gallagher indices).
  5. Fiscal and Social policy.
  6. Trade unions.
  7. Institutions. Measures of various institutional features, such as federalism, presidential/parliamentary system and referenda.

Geographical coverage

The dataset covers 35 OECD and EU countries.

Time coverage and updates

The dataset provides annual data from 1990 to 2009. Last update: August 10, 2011.


Generally speaking, the dataset is described in a fair amount of detail in the codebook, which is available for download from the website. However, the coding rules for variables reproduced from other sources are not specified in sufficient detail. Frequently the codebook does not specify how these variables are coded; it merely refers to the original source. This makes it unnecessarily time-consuming for users to find out how the variables are coded and what they measure.

Access conditions and cost

Available free of charge.

Access procedures

Predefined table.

Data formats


Comparability and data quality

Not examined. See chapter 5 in Rydland et al. (2008) for a general discussion of data on political institutions.


Armingeon, Klaus, and Romana Careja. 2008. Comparative Data Set for 28 Post-Communist Countries, 1989-2006. Institute of Political Science, University of Berne.

Armingeon, Klaus, Romana Careja, Panajotis Potolidis, Marlène Gerber and Philipp Leimgruber. 2011. Comparative Political Data Set III 1990-2009. Institute of Political Science, University of Berne.

Armingeon, Klaus, Marlène Gerber, Philipp Leimgruber and Michelle Beyeler. 2011. Comparative Political Data Set 1960-2009. Institute of Political Science, University of Berne.

Huber, Evelyne, Charles Ragin, John D. Stephens, David Brady and Jason Beckfield. 2004. Comparative Welfare States Data Set, Northwestern University, University of North Carolina, Duke University and Indiana University.

Lijphart, Arend. 1999. Patterns of Democracy: Government Forms and Performance in Thirty-Six Countries. New Haven and London: Yale University Press.

Rydland, Lars Tore, Sveinung Arnesen and Åse Gilje Østensen. 2008. Contextual data for the European Social Survey. An Overview and assessment of extant resources. NSD Report No.124, Norwegian Social Science Data Services (NSD).