Counting the world's poor: problems and possible solutions

The World Bank prepares and publishes estimates of the number of poor people in the world. While everyone knows that these numbers should be taken with a pinch of salt, the numbers are arguably important. In an institution where the reduction of poverty is the paramount objective, some overall yardstick of progress (or the lack of it) is required. The numbers are frequently quoted by politicians and by leaders of international organizations, including the Bank itself, who believe the numbers are effective for advocacy. Indeed, there is a long history of studies of poverty mobilizing support among the non-poor for anti-poverty policies. So it is important to know whether the world and national poverty counts are sound enough to support these uses. As recent discussions have made clear, the apparent lack of poverty reduction in the face of historically high rates of economic growth, both in the world as a whole, and in specific countries (most notably India), is providing fuel for the argument that economic growth does little to reduce poverty. How confident can we be that the data actually support these inferences? Are the changes in the poverty counts sufficiently well-measured to support conclusions about growth and poverty reduction? Should the World Bank stand ready to be judged by its success in reducing the current measures of world or even national poverty? If not, can better data collection or better methodologies improve the numbers?