Measuring Partisanship as a Social Identity in Multi-Party Systems

by Alexa Bankert, Leonie Huddy, and Martin Rosema

The resurgence of strong partisanship in the United States has attracted considerable attention among political scientists. Americans’ highly polarized ratings of the political parties and candidates are well documented and even extend to an unwillingness to fraternize with supporters of the other party. This raises questions as to whether or not strong partisanship and consequent party polarization is peculiarly American. Numerous political behavior scholars have argued that European citizens act in a less partisan fashion, basing their vote in considerations such as party performance and agreement with the party’s policy platform.

In our article, published recently online in Political Behavior, we take issue with the view that European partisanship is less influential than its American counterpart. We introduce a new scale that measures partisanship as a social identity using a series of eight items which ask respondents about the extent to which they had felt insulted when someone criticized their party, the frequency with which they referred to their preferred political party as “my party”, and other similar questions. Using large national surveys from the Netherlands, Sweden, and the United Kingdom, we demonstrate that this multi-item scale provides a very reliable indication of the strength of respondents’ partisan identity in all three countries despite their differences in electoral processes and overall partisanship levels.

We employ item response theory to show that when partisan identity is measured with the 8-item scale it provides a far better view of the intensity of someone’s partisan leanings than the traditional question asked in virtually all public opinion polls. This traditional question simply asks someone whether they are more or less close to the party, or a strong or not so strong partisan. In contrast, when assessed with eight items partisan identity provides a more finely grained measure of partisan identity strength that better reveals its influence on a range of political behaviors.

In the Netherlands, Sweden, and the UK, partisan identity was a more powerful predictor than the standard single-item measure of partisanship of voters’ willingness to vote for and actively support their political party. This is especially true for political actions motivated by partisans’ desire to directly advance the status of their party such as donating money to or volunteering for a party’s campaign. Based on these findings, we argue that past studies have underestimated the degree to which partisanship stimulates political participation in Europe. We also find that the partisan identity scale is a stronger predictor of in-party voting and political participation than holding a strong and consistent stance on a set of issues endorsed by one’s political party.

We consider the broader implications of our findings for the study of European partisanship and elections. Partisan identity is politically influential in Europe and promotes political engagement but it also exists at lower levels in some countries than found in the United States. This raises several crucial questions: Are declining levels of European partisanship associated with lower levels of political engagement? Do they contribute to greater electoral volatility? And do they open the way for personality-centered elections? By measuring partisanship with greater nuance we are better able to address these and other related questions concerning the importance and ongoing influence of partisanship within established democracies.



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