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	Social Identity Political Measurement	Group Identity Measurement
Field	Political Psychology	Political Psychology
Family	Process / pipeline	Process / pipeline
Year of origin	2015	2008
Originator	Leonie Huddy, Lilliana Mason & Lene Aaroe	Colin Wayne Leach et al.
Type	Self-report identity scale	Self-report identity scale
Seminal source	Huddy, L., Mason, L., & Aaroe, L. (2015). Expressive partisanship: Campaign involvement, political emotion, and partisan identity. American Political Science Review, 109(1), 1-17.	Leach, C. W., van Zomeren, M., Zebel, S., Vliek, M. L. W., Pennekamp, S. F., Doosje, B., Ouwerkerk, J. W., & Spears, R. (2008). Group-level self-definition and self-investment: A hierarchical (multicomponent) model of in-group identification. Journal of Personality and Social Psychology, 95(1), 144-165.
Aliases	Political Social Identity Scale, Partisan Social Identity Measure, Expressive Partisanship Scale	Group Identification Scale, Ingroup Identification Measure, Identity Centrality Scale
Related	4	4
Summary	Social identity measurement in political behavior applies social identity theory (Tajfel & Turner, 1979) to political groups, treating partisanship, ideology, or movement membership as a social identity rather than a mere instrumental affiliation. Huddy, Mason and Aaroe (2015) adapted Mael and Tetlock-style identity items into a partisan social-identity scale that measures expressive, emotionally charged group attachment and predicts campaign activity and political emotion better than issue agreement.	Group identity measurement assesses the strength and structure of a person's psychological identification with a social group, such as a party, nation, ethnic group, or movement. The Leach et al. (2008) hierarchical multicomponent model is a leading approach, decomposing in-group identification into self-definition (individual self-stereotyping, in-group homogeneity) and self-investment (solidarity, satisfaction, centrality), measured by a validated 14-item scale.