Most of a society’s middle holds a stable ~50% of income; the fight is between the ends. The Palma ratio ignores the calm middle and reads the tension directly: the top 10%’s share divided by the bottom 40%’s. Slide (or tap) to level the ends and watch it fall toward its equality floor.
The Palma ratio, computed live: the income share of the top 10% divided by the share of the bottom 40% — the measure Gabriel Palma proposed because the middle five deciles reliably hold about half of income, so inequality lives at the tails. Here n=10, so it is the richest one’s share over the poorest four. At perfect equality the ratio is its floor of 0.25 (the top tenth owns a tenth, the bottom two-fifths own two-fifths); a fail-loud self-check throws unless the base ratio exceeds the levelled ratio, which sits at 0.25.
A 10-person population makes ‘top 10% / bottom 40%’ a single-vs-four split; real Palma uses population deciles on survey data. The share arithmetic and the 0.25 equality floor are exact.