> That a person alive now is expected to die in the past? This seems an uncharitable interpretation. Instead, I expect that the value shown is the "expected a

> That a person alive now is expected to die in the past? This seems an uncharitable interpretation. Instead, I expect that the value shown is the "expected age of death" - "current age", which if your current age is beyond the average results in a negative number. FWIW and as you note, this isn't the most useful result since alive people can't die in the past unless we accept some sci-fi premises. > The correct method While we're on the topic... More correct? Many factors that would improve the prediction weren't collected and used but a better prediction would take those into account. So... Yes, your suggested method seems more useful and accurate yet I wasn't going for that goal so much as noting that it made sense to be that a lazy/naive/PoC/first implementation might get a negative result using exactly the formula above.