> we can only conclude that patio11's "true statement" is false by a pretty large margin. For it to be true, every birth in 2016 would have to have been to a woman who also gave birth in 2015.
So this has been bothering me, because if every birth in one year is to a woman who gave birth the previous year, and the years have equal birth rates, and we ignore aging in/out of the "fertile" demographic, then the odds of giving birth in one year given that you gave birth last year are 100%, well over 5x the population rate.
The claim is that the odds of giving birth this year given you gave birth last year are equal to the odds of giving birth this year given you're fertile, or in other words that, if you're fertile, whether you give birth this year is probabilistically independent of whether you gave birth last year. This is quite clearly false -- your odds of giving birth in one year are much lower, given you gave birth the year before, than your odds of giving birth in any randomly-selected year during which you're fertile. But my argument above is wrong.
For patio11's claim to be true, 6.1% of women who gave birth in one year would need to give birth again the next year. (Stated equivalently, 6.1% of people would need to have an older sibling born one calendar year before themselves.)
So this has been bothering me, because if every birth in one year is to a woman who gave birth the previous year, and the years have equal birth rates, and we ignore aging in/out of the "fertile" demographic, then the odds of giving birth in one year given that you gave birth last year are 100%, well over 5x the population rate.
The claim is that the odds of giving birth this year given you gave birth last year are equal to the odds of giving birth this year given you're fertile, or in other words that, if you're fertile, whether you give birth this year is probabilistically independent of whether you gave birth last year. This is quite clearly false -- your odds of giving birth in one year are much lower, given you gave birth the year before, than your odds of giving birth in any randomly-selected year during which you're fertile. But my argument above is wrong.
For patio11's claim to be true, 6.1% of women who gave birth in one year would need to give birth again the next year. (Stated equivalently, 6.1% of people would need to have an older sibling born one calendar year before themselves.)