Appendix B: Classifying European political parties

A new analysis from Pew Research Center classifies European political parties as populist using a three-source consensus method, drawing on expert surveys conducted in 2023 and 2024 [1]. The methodology relies on the 2024 Chapel Hill Expert Survey (CHES), the 2023 Populism and Political Parties Expert Survey (POPPA), and the PopuList 3.0 project. A party is defined as populist when at least two of these three measures classify it as such [1]. The CHES survey, conducted from October to December 2024, asked 609 political scientists to evaluate 279 parties across all European Union member states except Luxembourg, as well as parties in Iceland, Norway, Switzerland, Turkey, and the United Kingdom [1]. The POPPA survey, fielded between January and May 2023, gathered assessments from 324 experts on 312 parties in 31 European countries [1]. To measure anti-elitism, the CHES data averages two variables: a party's position on direct versus representative democracy and the salience of its anti-establishment rhetoric. Parties scoring 7.0 or higher on this average are classified as populist [1]. The POPPA dataset uses a “POPULISM_MEAN” score, an average of five indicators including Manichean worldview, belief in the indivisibility of the people, and anti-elitism. Parties scoring 7.0 or higher on this measure are also classified as populist [1]. The PopuList project, which examines parties that have won at least one seat or 2% of a national parliamentary election since 1989, relies on iterative collaboration among comparative and country experts to classify parties based on core ideological attributes [1]. Beyond populism, the analysis sorts parties into left, right, and center categories. Using the CHES “LRGEN” variable, where 0 is extreme left and 10 is extreme right, left parties score below 4.5 and right parties score above 5.5 [1]. The POPPA dataset uses a similar “LROVERALL” scale from 0 to 10, with the same thresholds. The report notes 100% agreement between the two surveys on the parties classified as populist [1]. The broader context of measuring political systems is reflected in the use of democracy indices, which are quantitative assessments of the state of democracy across countries and can vary in scope and the weight given to different democratic aspects [3]. While the Pew analysis focuses on European parties, populism has also been identified as a defining feature of major parties elsewhere, such as the Republican Party in the United States, which is described as a right-wing populist and nationalist party [4].