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 parties
on 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 crossnationally, 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.