by Carl Haub, senior demographer, PRB
As compelling a concept as it may be, life expectancy is an often-misunderstood demographic measure. Frequently, it is life expectancy at birth that receives the most attention, although we’re all aware we’re “living longer.”
Life expectancy results from life tables, sometimes referred to as actuarial tables. In a sense, a life table summarizes the mortality experience of a population in a given time period, often a year. Death rates are low for young people and naturally rise with age. But what matters is how much or how little these rates change and at what ages. As an example, consider life expectancy in the United States in 1940.