Index Rankings
Understanding composite indices like the HDI, Freedom House scores, and corruption rankings — what they measure and what they miss.
How Composite Indices Work
A composite index combines multiple indicators into a single score. The Human Development Index (HDI) combines life expectancy, education (mean years of schooling and expected years of schooling), and income (GNI per capita). Each component is normalized to a 0-1 scale, then the geometric mean produces the final score.
Other major indices include Transparency International's Corruption Perceptions Index (CPI), Freedom House's Freedom in the World scores, the World Press Freedom Index, and the Global Peace Index. Each uses different methodologies — some rely on expert surveys, others on hard data, and many combine both.