Trailhead: A campaign blog.

How To Handicap a Presidency

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.)

As the chart shows, Obama has a 93.2 percent chance of remaining healthy through one term in office, while McCain’s odds are 83.3 percent. After two terms, Obama’s odds drop to 86.0 percent while McCain’s sink to 68.1. To put it another way, if 1,000 identical John McCains were elected, 833 would still be healthy after one term, and 681 would still be healthy after two.

James Brooks, a senior actuary at Bragg, flushed out the details of how they built out their profiles for McCain and Obama. Were McCain and Obama totally healthy, they could expect to live healthily for an average of 12.2 years and 30.6 years, respectively. Bragg then factored in McCain’s degenerative arthritis—a keepsake of his POW years—as well as his history of melanoma and mild vertigo. For Obama, the actuaries considered his smoking habit, some minor upper respiratory problems, and history of cancer in his family. (While Obama has said he no longer smokes, you don’t get actuarial credit for it until you’re cigarette-free for 12 months.)