Poverty Measurement in the Presence of a 'Group-Affiliation' Externality

This paper considers the implications for poverty measurement of the observed fact that any individual's level of deprivation is a function not only of his own income, but of the general level of prosperity of the group to which he is affiliated. Individual deprivation functions are specialized to a form that reflects this 'group-affiliation' externality, and the resulting poverty measure is studied with respect to its properties, and its implications for poverty rankings. Mainstream approaches to measuring deprivation tend to neglect group-related externalities in favour of a certain thorough-going 'individualism'. This paper is a preliminary attempt at filling this gap.