1. What is global inequality? Global inequality is inequality between all citizens of the world. It treats the world as a single unit (as we normally treat individual countries). The data used to calculate global inequality come from the nationally-representative household income surveys that are increasingly (when available) corrected for the underestimation of top incomes using fiscal data. It also adjusts for the differences in price levels between countries by expressing all incomes in international (or PPP) dollars that in principle have the same purchasing power anywhere in the world. Income is defined as annual after-tax and after-transfers income per capita (where total household income is divided equally among household members).