How does the Human Development Index (HDI) measure life expectancy?

The Human Development Index (HDI) is a composite measure that assesses the overall development of a country by considering various dimensions of human well-being. One of the key components of the HDI is life expectancy, which measures the average number of years a person is expected to live from birth.

To calculate the life expectancy component of the HDI, the United Nations Development Programme (UNDP) uses data on the mortality rates of different age groups within a country. Specifically, they consider the probability of dying at each age, from birth to 85 years and above. This data is obtained from national vital registration systems, censuses, and surveys.

The life expectancy component of the HDI is calculated using a standardized formula that takes into account the life expectancy at birth and the maximum life expectancy observed globally. The formula is as follows:

Life expectancy index = (Life expectancy at birth - Minimum life expectancy) / (Maximum life expectancy - Minimum life expectancy)

In this formula, the minimum life expectancy is set at 20 years, representing a theoretical minimum survival age, while the maximum life expectancy is set at 85 years, representing the highest observed life expectancy globally.

By using this formula, the life expectancy index ranges from 0 to 1, with 0 indicating the lowest life expectancy and 1 indicating the highest. This index is then combined with other components of the HDI, such as education and income, to calculate the overall HDI score for a country.

The inclusion of life expectancy in the HDI reflects the understanding that a longer and healthier life is a fundamental aspect of human development. It recognizes that improvements in healthcare, nutrition, sanitation, and other factors contribute to increased life expectancy and overall well-being.

Overall, the HDI's measurement of life expectancy provides a comprehensive assessment of a country's development by considering the health and longevity of its population. It helps policymakers and researchers understand the progress made in improving the quality of life and identify areas that require further attention and investment.