May 28, 2024
On average, people have lived much longer than the period life expectancy at their time of birth
The data on this chart comes from the Human Mortality Database.
It shows that in 1930, people in France had a period life expectancy of 57 years. Period life expectancy is a metric that summarizes age-specific mortality rates in one particular year. This means that newborns would live 57 years on average if they experienced the same death rates at each age of their lives as those seen at each age in the population that year.
However, these newborns actually faced lower death rates than previous generations and lived an average of 69 years. This second measure — the average lifespan of a birth cohort — is called cohort life expectancy. It can only be calculated once all cohort members have died.
Period life expectancy is the more commonly reported “life expectancy” measure. However, these two measures are very different, and the gap can be large, as this data shows.
Read more on the difference between period and cohort measures →