A measurement scale for material deprivation: A model-based approach

The prevailing practice of defining classes of material deprivation based on the raw sum of a relatively small number of binary items has obvious advantages in terms of communication and ease of use. Do two people with the same raw score always have the same level of deprivation? This paper examines the methodological foundations of the raw score, comparing classical test theory with model-based test theory such as Rasch measurement and item response theories. After discussing the merits and limitations of the different approaches, the paper legitimizes the raw score when the assumptions of the Rasch model are met. Based on the analytical procedure of the Rasch model and using the pre-Covid data from the Survey on Income and Living Conditions, the paper also suggests how to develop a European scale for measuring material deprivation that ensures comparability across European countries.