HDi

HDI, or Human Development Index, is a summary statistic used by the United Nations Development Programme (UNDP) to measure and compare levels of human development across countries. Introduced in the 1990 Human Development Report, the HDI provides a single composite figure on a 0 to 1 scale, with higher values indicating higher human development.

It combines three dimensions: health, education, and standard of living. Health is measured by life expectancy at birth. Education combines mean years of schooling for adults aged 25 years and over and expected years of schooling for children entering school. Standard of living is proxied by gross national income per capita, converted to purchasing power parity terms.

To compute the HDI, each dimension is converted into a normalized index against predefined minimum and maximum values, and the three indices are aggregated, typically using a geometric mean. The resulting value ranges from 0 to 1, where 1 represents the highest possible human development.

HDI is widely used to rank countries and monitor progress over time. It has limitations, including sensitivity to data quality and currency fluctuations in GNI PPP, and it does not, by itself, capture inequality or distribution. The Inequality-adjusted HDI (IHDI) and related indices such as the Gender Inequality Index supplement the HDI by incorporating disparities in health, education, and income. Overall, the HDI remains a key reference in international development discourse for assessing broad human development trends.