The Flaw of Averages: Why We Underestimate Risk in the Face of Uncertainty

CHAPTER 38

The Flaw of Averages in Health Care

The great radio comedian Jack Benny was confronted in one of his skits by a mugger who demands, “Your money or your life!” Benny, whose stage persona was notoriously stingy, does not respond immediately. “Your money or your life,” repeats the robber.

“I’m thinking it over,” responds Benny.

This story highlights a dilemma concerning the U.S. health care system. Although most of us would spend anything to save our own life or the life of a loved one, universal health care is viewed by some as a mugger who demands, “Your money or someone else’s life.” As a nation, we’re still thinking it over.

But regardless of which side of this debate you are on, you can hardly object to getting more health care benefits for the buck. One way to accomplish this is through more precise targeting of treatment.

Treating the Average Patient

That the average adult patient has one breast and one testicle should be ample warning not to apply health care with too broad a brush. A more subtle example involves Simpson’s paradox and the kidney stone treatment presented earlier. When you averaged results over the entire population, treatment A was worse than treatment B. But when you zoomed in to focus on groups of patients with either large or small kidney stones, treatment A was found to be superior to treatment B in both groups. Here the treatment that was best for the average patient was worst for every individual patient!

Poorly targeted treatment is ...