Because the underlying household surveys differ in method and in the type of data collected, the distribution indicators are not strictly comparable across countries. The following sources of noncomparability should be noted. First, the surveys can differ in many respects, including whether they use income or consumption expenditure as the living standard indicator. Income is typically more unequally distributed than consumption. Consumption is usually a much better welfare indicator particularly in developing countries.
Individuals differ in age and consumption needs.
Differences between countries in these respects may bias distribution comparisons. World Bank staff have made an effort to ensure that the data are as comparable as possible. Whenever possible, consumption has been used rather than income. Households have been ranked by consumption or income per capita in forming the percentiles, and the percentiles are of population, not households. The income distribution and Gini indexes for high-income countries are directly calculated from the Luxembourg Income Study database.