Charlie,

A third approach is to pull a number from an actuarial life table, such as is found at the SS website. But the number can be pulled from the table in several ways, one which is your method of taking the 'half-life' of the remaining cohort, given one’s present age. But that doesn’t tell me anything about the distribution of the right-hand tail, i.e., the likelihood of losing the bet that one won’t live longer than that projected average, nor by how much.

My only point of disagreement was basing the distribution on age 0 rather than current age. I agreed completely with your insistence at looking at the distribution, not any one number. That's why I long ago took the SSA actuarial table you linked to into a spreadsheet and performed my own calculations. My spreadsheet shows my numbers for every age from 59 to 99 (with a graph). So, as of when I ran it at age 59, it showed I had a 25.3% chance of reaching at least 88. A one in four chance of being destitute doesn't appeal to me! Looking out to age 92 gave a 12.2% chance, which seems a lot less intimidating for me as nobody in my line got past mid-eighties. I may not have used standard deviation but I still got the full picture.

RH