Measuring populism as a demand-side phenomenon: A psychometric evaluation of populist attitudes across Europe

The majority of populism research focuses on its definition, its constructions, its causal factors and its influence, and all of this particularly on the supply-side of politics. Less research focuses on the measurement and empirical evaluation of populist attitudes, i.e. the demand-side of populism. As of recent, a number of prominent studies have converged towards a set of survey items to empirically analyse harmonised populist attitudes. These items are either applied in a non-European cross-national context or in a single country. Additionally, throughout the literature, the validity and reliability of these proposed survey items, as a measurement of populist attitudes, often remain assumed rather than empirically tested. This paper contributes to these last two debates by (i) providing a cross-national analysis of populist attitudes, and (ii) evaluating the items that measure populist attitudes through detailed psychometric analysis. We use six established and two innovative items from the LIVEWHAT survey (nine European countries, n = 18370) and apply both classical test theory and item response theory to them. The initial results of our analysis indicate the current operationalisation of the populism scale, while capable of measuring latent populist attitudes to some extent, fails to capture the full range of the concept in our cross-national sample. Specifically, they appear to only capture moderate populist attitudes. This would indicate the scale items are better used to measure a continuum that goes from moderate opposition to populism to a relatively weak endorsement of populism.