Start counting the poor in India and you are bound to get into controversy. In “A Comparative Perspective on Poverty Reduction in Brazil, China and India,” Martin Ravallion (October 2009) calculates that 42% of the population in India in 2005 lived in households with income per person below US$1.25 a day (converted using purchasing power parity exchange rates for consumption in 2005). But he finds only 20% of the population under the US$1.25 poverty line when using a different method as a sensitivity test. The difference is huge. One number is twice the other and corresponds to two hundred million people (more than the whole population of Brazil!).
Ravallion repeats the exercise and finds that in Brazil, in 2005, the population who lived in households with income per person below US$1.25 a day (converted using purchasing power parity exchange rates for consumption in 2005) is 8%. When using the alternative sensitivity test method, it is 10%. Compared to India, the difference is small (2% of the population) between the two measures.
I suspect that instead of trying to calculate the number of people with less than US$ 1.25 a day, policies for poverty reduction should focus on the bottom quintile of the population: the 20% poorest group in the country.
One of my reasons is that inequality matters. Think of poverty as a relationship.