The life expectancy at age x, denoted
, is then calculated by adding up the probabilities to survive to every age. This is the expected number of complete years lived (one may think of it as the number of birthdays they celebrate). 
Because age is rounded down to the last birthday, on average people live half a year beyond their final birthday, so half a year is added to the life expectancy to calculate the full life expectancy.
Life expectancy is by definition an arithmetic mean. It can be calculated also by integrating the survival curve from ages 0 to positive infinity (the maximum lifespan, sometimes called 'omega'). For an extinct cohort (all people born in year 1850, for example), of course, it can simply be calculated by averaging the ages at death. For cohorts with some survivors it is estimated by using mortality experience in recent years.
-----------------------Washington Times
... 2003 was the first time the average life expectancy of all U.S. women, regardless of race, exceeded 80 years ...
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seniorjournal.com
Headline: Rich White Men Doing the Best in Fight to Extend Longevity in U.S.
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very local stats
1 comment:
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