Title:	The Dynamics of Ideological Dimensionality in Sweden 1982–2022
DNr:	NAISS 2025/22-1319
Project Type:	NAISS Small Compute
Principal Investigator:	Jakob Ahlbom <jakob.ahlbom@statsvet.su.se>
Affiliation:	Stockholms universitet
Duration:	2025-09-26 – 2026-10-01
Classification:	50601
Keywords:

Abstract

The ideological structure of public opinion in Western democracies has been described as increasingly complex, with new cultural value conflicts intersecting with traditional left–right politics. While some forces expand the dimensionality of ideology, others compress it back into a more constrained one-dimensional form. To understand these dynamics, I study Sweden as a case from 1982 to 2022 using data from the Swedish National Election Studies (SNES). These surveys provide repeated cross-sectional measures of citizens’ political attitudes and represent one of the most extensive time series in the world. The project applies advanced Bayesian item response theory (IRT) models to estimate how the latent ideological space evolves over time. The models allow me to trace both expanding and compressing forces shaping the structure of ideology in mass publics. Pilot runs confirm that the code is functional, but runtime and memory demands are prohibitive on standard desktop computers. The analyses therefore require access to high-performance computing (HPC) resources, where parallel MCMC chains, checkpointing, and large memory capacity enable estimation of these dynamic models. The results will contribute to comparative research on the evolution of ideological structures, with broader implications for the study of political conflict, party competition, and democratic representation.