In theory, a poverty line can be defined as the cost of a common (inter-personally comparable) utility level across a population. But how can one know if this holds in practice? For groups sharing common consumption needs but facing different prices, the theory of revealed preference can be used...

We assess the developing world's progress in reducing poverty during the late 1980s using new data on the distribution of household consumption or income per person for 44 countries. Local currencies are adjusted to purchasing power parity. To assess robustness, restricted dominance tests are...

The authors estimate that in 1985 about one in five persons in the developing world lived in poverty, judged by the standards of the poorest countries. This rises to one in three at a common, more generous, poverty line. The aggregate consumption short-fall of the poorest fifth is about one half...

Drawing on 297 national sample surveys spanning 88 countries, we find that there was a net decrease in the overall incidence of both absolute and relative consumption poverty between 1987 and 1998. But it was not enough to reduce the total number of poor by various definitions. The incidence of...