Measuring poverty on a global scale requires establishing a uniform poverty level across extremely divergent economies, which can result in only rough comparisons. The World Bank has defined the international poverty line as U.S. $1 and $2 per day in 1993 Purchasing Power Parity (PPP), which adjusts for differences in the prices of goods and services between countries. The $1 per day level is generally used for the least developed countries, primarily African, the $2-per-day level is used for middle-income economies such as those of East Asia and Latin America.