Three sides of the same coin? comparing party positions in VAAs, expert surveys and manifesto data

Existing research on political parties' policy positions has traditionally relied on expert surveys and/or party manifesto data. More recently, Voting Advice Applications (VAAs) have been increasingly used as an additional method for locating parties in the policy space, with a closer focus on concrete policy issues. In this manuscript, we examine the reliability of party positions originated from a VAA, utilising the euandi longitudinal dataset, which provides data on positions of over 400 unique political parties across 28 EU member states from the European Parliament elections of 2009, 2014 and 2019. We cross-validate euandi data with the Comparative Manifesto Project (CMP) and the Chapel Hill Expert Survey (CHES). Our results attest the reliability of the euandi trend file vis-a-vis remaining data sources, demonstrating the validity of VAA-based methods to estimate the policy positions of European political parties. Convergence is especially high with CHES party placements. We also explore the sources of divergence in the estimation of policy positions across the three methods, finding little evidence of a systematic source of bias in the estimates between datasets. We conclude with an inventory of arguments in favour of party position measurements used by VAAs for the study of policy-making in European democracies.