A global scale of economic left-right party positions: cross-national and cross-expert perceptions of party placements

We examine the cross-national comparability of expert placements of political partieson the economic left-right dimension using a novel dataset combining data from Europe, Latin America, Australia, Israel, Canada, and the United States. Using anchoring vignettes and Bayesian Aldrich-McKelvey Scaling (BAM), we assess evidence of geographic and expert-level differential item functioning (DIF) in how experts interpret the left-right scale. We find statistically significant but substantively small variations in how experts perceive party positions cross-nationally, particularly in terms of directional bias and the spread of their ideological placements. While the correlation between “raw” survey scores and DIF-corrected estimates is high (0.992), we observe meaningful deviations for individual parties, with larger discrepancies between rather than within regions. These results indicate that the economic left-right dimension exhibits broad consistency in expert understanding across countries, yet researchers should still exercise caution when making cross-national comparisons, particularly across regions where expert perceptions show greater variation.