Duration and Multidimensionality in Poverty Measurement

This paper unites two strands of the literature on subgroup decomposable poverty measurement originating from Foster, Greer and Thorbecke (1984) by incorporating information on both multiple dimensions and multiple periods. This generalises the Alkire and Foster (2011a) measure into a dynamic setting. In doing so, it introduces two variants of the ‘transfer’ axiom: one that gives increasing weight to individuals whose deprivations are concentrated as repeated dimensions in a specific period (what we term ‘breadth’) versus one that gives increasing weight to individuals whose deprivations are concentrated as repeated periods in a specific dimension (‘length’). The measure is able to differentiate between both aspects of poverty and consequently allows the assignment of different weights to each aspect. This makes it well suited to make comparison across subgroups when individual longitudinal data is available. We apply the proposed measure to longitudinal data from China where we compare differences in the estimate of poverty relative to existing measures.