Poverty
The poverty line threshold of $1.90 per day, as set by the World Bank, is controversial. Each nation has its own threshold for absolute poverty line; in the United States, for example, the absolute poverty line was US$15.15 per day in 2010 (US$22,000 per year for a family of four), while in India it was US$1.0 per day and in China the absolute poverty line was US$0.55 per day, each on PPP basis in 2010. These different poverty lines make data comparison between each nation's official reports qualitatively difficult. Some scholars argue that the World Bank method sets the bar too high, others argue it is low. Still others suggest that poverty line misleads as it measures everyone below the poverty line the same, when in reality someone living on $1.20 per day is in a different state of poverty than someone living on $0.20 per day. In other words, the depth and intensity of poverty varies across the world and in any regional populations, and $1.25 per day poverty line and head counts are inadequate measures.
Bottom of the pyramid
The standards and benchmarks developed – for example less than $2.5 a day – always tell us about the upper limit of what we call the BoP, and not actually about its "base or bottom". The fact is that the bottom or the base is much much lower. Even going by the official definition, for example in India the Rangarajan Committee after re-examining the issue of poverty defined the poverty line in 2011-12 at INR 47.00 ($0.69) per capita per day for urban areas and INR 32.00 ($0.47) per capita per day in rural areas (June,2016 conversion rate), obviously much less than the $2.5 per day benchmark. This again is the "upper layer" of the poor as defined by the Rangarajan Committee. Where is the actual bottom? and how low? This can perhaps only be visualised by observing the slums right in the hearts of the cities in the developing countries.