1. The Income Distribution ( D ) . There are different ways in which income distribution data can be presented. A particularly convenient form is one which indicates the cumulative income share of each cumulated decile of the population, arranged from poorest to richest. That is, the data are presented in such a way that we have information on the income share of the poorest 10 per cent of the population, the income share of the poorest 20 per cent, the income share of the poorest 30 per cent,…, and so on, until we have accounted for all 100 per cent of the population. The income distribution is thus essentially depicted in a two-column table in which the first column lists the cumulated deciles of the population in ascending order of income and the second provides the cumulated income share corresponding to each cumulated population share.
  2. The Poverty Line (z) . The poverty line is a level of income such that all persons with incomes less than this level are considered to be poor .
  3. The Mean Income of the Distribution (m) . This is just the average income of the reference population.