Use of extended IRT models for Composite Indicator development

Item response theory (IRT) models are tools developed in psychometrics and applied primarily to validate, analyze, and score tests and questionnaires measuring abilities and attitudes. However, their potentials extend well beyond the education and psychometric fields. In fact, recent developments of these models allow us to pursue two key objectives of the social sciences, that is, verifying and retaining the multidimensionality of the data, either with an explorative or a confirmatory approach, and classifying units into homogeneous groups as regard to the identified relevant dimensions. Concurrently accounting for multidimensionality and classification instances is a step forward compared to statistical methods of data complexity reduction concerned either, on one side, with the structure of variables, or with the structure of units on the other, as it allows us to explain and qualify the differences between clusters of units alongside the distinctive latent dimensions underlying the data at issue.