Economy > Inequality > Gini coefficient > Level: Countries Compared

DEFINITION: Income is defined as household disposable income in a particular year. It consists of earnings, self-employment and capital income and public cash transfers; income taxes and social security contributions paid by households are deducted. The income of the household is attributed to each of its members, with an adjustment to reflect differences in needs for households of different sizes (i.e. the needs of a household composed of four people are assumed to be twice as large as those of a person living alone).

Income inequality among individuals is measured here by five indicators. The Gini Coefficient is based on the comparison of cumulative proportions of the population against cumulative proportions of income they receive, and it ranges between 0 in the case of perfect equality and 1 in the case of perfect inequality. The mean log deviation is the average value of the logarithm of the ratio of mean income to the income of each decile. The squared coefficient of variation is the variance of average income of each decile, divided by the square of the average income of the entire population. The P90/P10 ratio is the ratio of the upper bound value of the ninth decile (i.e. the 10% of people with highest income) to that of the first. The P50/P10 ratio is the ratio of median income to the upper bound value of the first decile. The mean log deviation and inter-decile ratios have a lower value of 1 and no upper bound, while the squared coefficient of variation has a lower bound of 0 and upper bound of infinity.