Absolute poverty is sometimes measured by the number, or “headcount,” H, of those whose incomes fall below the absolute poverty line, Yp. When the headcount is taken as a fraction of the total population, N, we define the headcount index, H/N. The poverty line is set at a level that remains constant in real terms so that we can chart our progress on an absolute level over time. The idea is to set this level at a standard below which we would consider a person to live in “absolute human misery,” such that the person’s health is in jeopardy.