GapMinder: Life Expectancy PPT

Life expectancy is an important measure of a country’s overall health. This Power Point presentation explains the basics of life expectancy and is available at:

Background Information

  • Life expectancy is an average. Most people live either much longer or much shorter than what the life expectancy indicates.
  • When life expectancy is low, this is mostly due to a very high child mortality rate. Those that survive the dangers of childhood can expect to live to a relatively old age, even in countries with very low life expectancy.
  • Mean age of death during a year. Imagine if we looked up all the obituaries during a single year, noted the ages at death and calculated the mean of all those ages. That would be the mean age of death.
  • Cohort life expectancy. Cohort life expectancy is the average age at death of those born in a particular year. Let us, for example, look up all those that were
    born in Sweden in, say, 1860. In that year 133,162 babies were born in Sweden. By 1965 the last of them had died, at the age of 105 year.If we calculate the mean of the ages at death of all of these 133,162 people we find it is 48 years. This is the cohort life expectancy for 1860.
  • The forecast mean age of death of those born in a particular year. If we are happy with the cohort measure above but do not want to wait more than 100 years to obtain it for 2007, then we could perhaps attempt to make some sort of prediction. This would then be a forecast cohort life expectancy for 2007.
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