On the US Social Security Admin's site, they present an actuarial table.  The table for 2004 is the most recent, but conditions in this country haven't changed that much since then that the numbers would be different.

The left column on the table is the age at the next birthday of the person.   Then, there are two sets of three columns each, one for men and one for women.  Men, on the left.  

The first of these three columns represents the probability of the person dying before the next birthday.  So, for a man who is, say, coming up on his 55th birthday, you look and see that the actuaries predict a probability he won't see this next birthday of .007921.  This is a table derived from "large numbers", i.e., for the population as a whole.  That is, it does not take into account individual differences in health, how well a particular individual takes care of themselves, family history - any of that.

To see the probability of living a certain number of years into the future, you add the probabilities.

So, what do the actuaries say?

McCain (aged 72)

next      probability of

birthday  his seeing it

73           0.036086

74           0.039506

75           0.043415

76           0.047789

Sum         0.166796

Obama (aged 47)

next      probability of

birthday  his seeing it

48           0.004805

49           0.005208

50           0.005657

51           0.006134

Sum         0.021804

In other words, McCain is - purely on age alone - more than 8 times a likely to die before the end of the 2009-2013 term than is Obama.  And this does not take into account McCain's 5 and a half tortuous years of POW torture, nor his four known bouts of cancer, and surely not the hard living to which he subjected himself.

But, more than that, you get better odds playing Russian Roulette.  There, the probability of getting a loaded cylinder is 1 in 6, or 0.166666.  McCain's probability:  0.166796.

Would you play Russian Roulette with your and your kids' future?

h/t Balkinization for the idea