Replication material for: Kuhn, Ursina & Marquis, Lionel (forthcoming). Does ideological polarization promote political engagement and trust? Evidence from Swiss panel data, 1999‒2023

This study explores whether ideological polarization increases political engagement and trust, both being central elements of civic culture. Polarization can clarify political positions and so simplify the formation of opinions, increase the stake of elections, and offer more options to citizens. To estimate the impact of polarization from a causal perspective, we exploit variation within individuals over time using individual-level data from the Swiss Household Panel spanning from 1999 to 2023, amounting to 178,251 observations from 28,187 persons. Ideological polarization at the individual level is measured by a process of increasing extremity of the self-position on the left-right scale. In addition, we test how polarization of co-habiting household members has spillover effects on political engagement and trust. For political engagement, we adopt a comprehensive approach, focusing on interest in politics, participation in popular votes, party identification and frequency of political discussions as dependent variables. Political trust is measured as confidence in the federal council. To analyze the data, we primarily use fixed effects models, complemented by pooled OLS model, and cross-lagged models to address reverse causality. Results show that ideological polarization does promote engagement, but has a weak negative impact on political trust. This effect remains significant when controlling for affective polarization. Additionally, there is an overall increase in political engagement and decrease in political trust if partners living in the same household become more extreme in their ideological preferences.