Several blogs and publications have recently attempted to calculate the odds that John McCain will live another four or eight years, bringing an actuary’s dispassion to the delicate subject of the Republican nominee’s age. Based on the Social Security Administration’s life expectancy tables , the Times Online concluded that McCain will live another 13 years, while a Daily Kos diarist calculated that McCain’s odds of dying naturally during his first term were 15 percent. His odds of not surviving two terms were nearly 1-in-3. Politico arrived at similar figures .
Actuaries get rightfully nervous when journalists get their hands on these tables. The odds that a 72-year-old male will die in the next year are calculated from large data sets and apply rather poorly to individuals. To get a better picture of how both McCain and Barack Obama fare, an actuarial firm in Atlanta called Bragg Associates made a series of calculations tailored to the health records that both candidates made public. Rather than estimating life expectancy, Bragg specializes in "health expectancy," the ability to function lucidly and without assistance—the kind of qualities one hopes for in a president. As the Atlanta Journal-Constitution reported , Bragg originally concluded that McCain has 8.4 years of good health ahead of him while Barack Obama has 21.9.
At Slate ’s request, Bragg fleshed out those predictions into a series of probabilities that the two candidates will remain healthy in office year by year. Their findings are below. (Mouse over a data point to see the percentage value.)