This open access publication deals with the operationalisation of the welfare state as an independent variable.To study how welfare states affect social inequality, individual behaviour, attitudes and more in different countries, an empirical operationalisation of the welfare state or specific elements of social policy is required. However, this operationalisation is fraught with some important problems. These problems essentially relate to one point: while there are a large number of contributions dealing with the measurement of differences between welfare states per se and as a dependent...