Life expectancy (or the expectation of life) is the average length of life remaining to be lived by a population at a given age. It is computed in the process of building a life table and can be computed for any age in the life table. Life expectancy at birth is the most commonly presented value because this measure provides a succinct indicator of mortality that reflects mortality conditions across the age range and is unaffected by the age structure of the actual population and thus can be compared across populations. The symbol used to represent life expectancy is &NA;_x where x represents an exact age.

Life Expectancy in the United States

In 1996, life expectancy at birth, &NA;₀, in the United States was 76.1 years; at age 65, &NA;₆₅ was 17.5 years; and at age 85, &NA;₈₅ was 6.1 years (Anderson 1998). These figures can be interpreted to mean that if...