The 2020 Democratic Presidential Nomination Campaign

Percy, that’s not how life expectancy is calculated. It takes all people who are 77 years old this year and then takes the number of those people who survive just one more year, number who survive just two more years. etc. and averages those life spans. Of course, those people haven’t actually died yet so the numbers are taken from a model that is base on prior years data. The parameters of that model are updated every year as new data (death statistics) becomes available. Until recently, that model has been found to be consistently slightly pessimistic but in the past couple of years has reversed to being slightly optimistic, and this is primarily due to drug (pain treatment) overdoses. For people already 77 years old, the curve of survival years looks somewhat like the tail of a gaussian distribution with fewer people surviving N+1 years than survive just N years. That curve has a very long tail and predicts that many of those people will survive well into their hundreds. The most important thing to note is that that life expectancy number is nothing more than an average number derived from an abstract model and has absolutely no relevance to any particular individual. That individual’s continued life span will depend on many personal factors such as current state of health, life style, risk behaviors, and probably most of all, luck (e.g., not stepping in front of an 18 wheeler).