What is the definition of life expectancy? How to measure it?

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Life expectancy is defined as the average number of years a person can expect to live, based on statistical estimates of mortality rates within a specific population. It reflects the overall health and longevity of a population and can vary by factors such as gender, geography, and socioeconomic status.

To measure life expectancy, researchers typically construct life tables, which incorporate age-specific death rates derived from census and vital statistics data. These tables calculate the average remaining years of life for individuals at various ages, allowing for the estimation of life expectancy at birth and at specific ages within the population.