In practice, this may be translated as poverty experienced at two distinct points in time, separated by several years (Hulme and Shepherd, 2003). Severe poverty (people living significantly below the extreme poverty line) can be used as a proxy when measuring chronic poverty - this is necessary since the panel data which allow analysis of poverty over time are not available for more than a few countries. Severe poverty is usually less widely experienced than chronic poverty, but most severely poor people are also chronically poor (McKay and Perge, 2011).