The income groupings use GNI per capita (in U.S. dollars, converted from local currency using the Atlas method) since they follow the same methodology used by the World Bank when determining it’s operational lending policy. While it is understood that GNI per capita does not completely summarize a country’s level of development or measure welfare, it has proved to be a useful and easily available indicator that is closely correlated with other, nonmonetary measures of the quality of life, such as life expectancy at birth, mortality rates of children, and enrollment rates in school.