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. However, gradual intakes into this field are being made, with scholars gradually but systematically converging around the item battery originally designed by Hawkins and Riding (2010). As of today, different variations of this battery are being used to measure populist attitudes across the Americas and Europe (both single country and cross-nationally). Yet, the validity and reliability of these survey items, as a measurement of populist attitudes, often remain assumed, rather than empirically tested. This chapter contributes to these last two debates by (i) providing a cross-continental analysis of populist attitudes, and (ii) evaluating the items that measure populist attitudes through detailed psychometric analysis. We use different data sources across the Americas and Europe and apply both classical test theory and item response theory to them. Our initial results indicate this question battery does measure populist attitudes; yet its analytical scope fails to capture the full range of the concept and remains limited to ‘moderate populism’. Therefore, we recommend extensive exploratory testing of potential items to measure populist items so as to (eventually) complement these existing items.
