How an equality curve turns a society into a picture
To draw the curve, arrange people from the least to the most resourced, then track two running totals: what fraction of the population has been counted, and what fraction of the resources they hold. At the halfway point on the population axis, for example, the curve shows the share held by the less-resourced half.
That makes the graph more informative than a simple average. Two societies can have the same average income while distributing it very differently; their curves reveal whether gains are spread broadly or cluster near the top. The further the curve dips below the equality diagonal, the larger the gap between those cumulative shares.
Turning the curve into a single number
The curve can also produce the Gini coefficient, a summary of inequality based on the area between the curve and the equality line. A curve close to the diagonal means a small area and a lower Gini; a curve that bows farther away means a larger area and a higher Gini. The number is useful for comparisons, but it compresses a whole distribution into one measure, so it cannot show exactly where inequality is concentrated.
The result also depends on what is counted. A graph of income can look different from one of wealth, and comparisons can change depending on whether figures are measured before or after taxes and transfers. The curve’s practical value is that it makes the question visible: not just how much a society has, but how the running total accumulates as you move from its least-resourced members to its richest.
