How to calculate Life Expectancy
Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of their birth, their current age and other demographic factors including sex.
Life expectancy is the most influential factor which is used by the insurance companies to determine life insurance premiums.
Life expectancy is calculated by constructing a life table. The only raw data needed are the population and age-specific deaths data in 5 year age bands. All other columns of data including expectation of life is calculated from these tables.
Detailed calculations and column definitions
- Width of the interval (n)
The number of years in each age interval. For example for the <1 age group n=1, for the 1–4 age group n= 4 and for all other age groups including 85+ n=5.
2. Average proportion of the year lived by those who die (nax)
Usually it is assumed that death occurs uniformly across time and that on average people will live 0.5 of the interval before death. However, there are some cases where we know that death does not occur uniformly across time within age groups. For example, for those aged under 1 we assume that the average proportion of the year lived by those who die is 0.1 .
3. The probability of dying between age x and x+n (nqx)
4. The probability of surviving (npx)
5. Number of persons alive at the start of the interval (Ix)
6. Number of deaths between age x and x+n (ndx)
7. Number of person years lived between age x and x+n (nLx)
8. Total number of person years lived after age x (nTx)
9. Expectation of life (ex)
Example
I have calculated the Life expectancy for Rajasthan, India (District Wise). Please share your views on it.
