A common measure of income inequality that can be derived from column 3 is the ratio of the incomes received by the top 20% and bottom 40% of
the population. This ratio, sometimes called a Kuznets ratio after Nobel laureate Simon Kuznets, has often been used as a measure of the degree of inequality between high- and low-income groups in a country. In our example, this
inequality ratio is equal to 51 divided by 14, or approximately 3.64.
To provide a more detailed breakdown of the size distribution of income,
decile (10%) shares are listed in column 4. We see, for example, that the bottom