The Human Development Index (HDI) is a statistical tool developed by the United Nations Development Programme (UNDP) to measure the level of human development in countries around the world. The HDI is based on three dimensions of human development: a long and healthy life, access to knowledge, and a decent standard of living.
The three components of the Human Development Index are:
- Life expectancy at birth: This is a measure of the average number of years a person is expected to live at birth. It reflects the overall health and well-being of a population.
- Education: This is measured by two indicators: mean years of education and expected years of schooling. Mean years of education is the average number of years of education received by people aged 25 and older. Expected years of schooling is the number of years of schooling that a child can expect to receive in their lifetime.
- Gross National Income (GNI) per capita: This is a measure of the average income per person in a country, adjusted for purchasing power parity.
The HDI combines these three dimensions into a single composite index, which is used to rank countries based on their level of human development. The index ranges from 0 to 1, with higher values indicating higher levels of human development. When referring to the world's least developed countries, the term usually refers to the lowest range of the index.
The Human Development Index is widely used as a tool for measuring and tracking progress in human development, and is used by policymakers, academics, and development practitioners around the world. However, the index has been criticized for its narrow focus on certain aspects of human development, and for its failure to capture other important dimensions of human well-being, such as social and political freedoms, gender equality, and environmental sustainability.