The simple answer is that micromort exposure is not independent of age: in expectation, a larger proportion of 80-year-old Americans will die within the next day than of 30-year-old Americans.
Based on 1, a 30-year-old is ~6 micromorts/day, rising to ~180 by age 80! On the other hand I’m a little suspicious of their numbers, because the female death rate is lower than male in literally every age group, and by eyeball it seems too much to explain by surviving longer into the 85-and-over group. 2 is a nice overview of life expectancy dynamics, including a section on age-specific mortality.
I figured it had something to do with different ages. At some level it still felt like if the micromort-based estimate of lifespan is 124 years, then someone group should have a life expectancy that long. But based on your comments, maybe the real issue is that, say, a baby that dies on the first day experiences 1 million micromorts per day, while someone who lives to be 100 experiences (1 million)/(365.25 days per year x 100 years) = 27 micromorts per day.
Wait, something still doesn’t make sense, because even at age 100, 27 per day on average is more than the 24 per day that we get from using deaths in a year.
There are a lot of young people who have not yet reached the point in their life where their micromort count increases dramatically. The expected average per person per lifetime being off does not matter; we do not include the risk that the young people will have when they are older, probably much higher than they have now, in our calculation.
The simple answer is that micromort exposure is not independent of age: in expectation, a larger proportion of 80-year-old Americans will die within the next day than of 30-year-old Americans.
Based on 1, a 30-year-old is ~6 micromorts/day, rising to ~180 by age 80! On the other hand I’m a little suspicious of their numbers, because the female death rate is lower than male in literally every age group, and by eyeball it seems too much to explain by surviving longer into the 85-and-over group. 2 is a nice overview of life expectancy dynamics, including a section on age-specific mortality.
I figured it had something to do with different ages. At some level it still felt like if the micromort-based estimate of lifespan is 124 years, then someone group should have a life expectancy that long. But based on your comments, maybe the real issue is that, say, a baby that dies on the first day experiences 1 million micromorts per day, while someone who lives to be 100 experiences (1 million)/(365.25 days per year x 100 years) = 27 micromorts per day.
Wait, something still doesn’t make sense, because even at age 100, 27 per day on average is more than the 24 per day that we get from using deaths in a year.
There are a lot of young people who have not yet reached the point in their life where their micromort count increases dramatically. The expected average per person per lifetime being off does not matter; we do not include the risk that the young people will have when they are older, probably much higher than they have now, in our calculation.