Yeah I figured that 80 was a pretty good approximation because the average life expectancy in the US is 77. It surprisingly doesn't increase as much I would have expected as you age so I didn't account for that effect.
Yea. It's kind of the same error, in a way, as people who assume that there were no old people in the middle ages. The overwhelming majority of the increase in expected lifespan between then and now comes from drastic decreases in the infant and child mortality rates. While current medicine is only really making slow, incremental progress on letting the oldest people live longer, even if this was the bulk of the advancement you wouldn't see the kind of movement on overall life expectancy you'd get out of reducing those, and that's just on the pure statistical basis of how the metric is constructed. But on top of that, I think it's nearly impossible to understand just how many infants used to be stillborn, and how many diseases we essentially eliminated. The death of a child from an illness used to be a fairly common tragedy, now it is a rare one.
It's just a little internet toy that probably cashes out to be a slightly more impactful version of "memento mori", but you could add a little backend complexity without collecting any more demographic information and get a more accurate life expectancy given only one's current age from extant actuarial tables. If you wanted to be extra cheeky, you could have it adjust on a regional basis based on IP address too
Well, average life expectancy in the middle ages was in the low 30s or high 20s, but the child death factor does not bring the typical old person age to the 80s that we're used to from today, but into the late 50s, early 60s. That was an old person.
As for making the predicion more accurate, it's a rabbit hole you'd rather not enter. Whether you smoke or not or whether you live in a big city or not or your social class all have much higher impact than whether your IP is from Spain or Poland or Florida. Including people with the time and means to browse such website are a very select group. Not even speaking of VPNs hiding your actual geolocation. Whatever you do beyond "let's shoot at 80 for approximate time" may be making things worse.
Yeah someone who is 40, comes out at roughly 82 which I thought was close enough. Also it is funny to enter famous old people's birthdays and see "110% complete".
