In this edition of Fun With Statistics we’ll explore why it is important to really read every word, and understand the sequence of data analysis, in a statistical argument. With a hat tip to Donald Luskin at The Conspiracy to Keep You Poor and Stupid, there’s a bit of controversy over Rudy Giuliani’s recent comments on healthcare. First, Rudy’s comment:
My chance of surviving prostate cancer ¬ and thank God I was cured of it ¬ in the United States? Eighty-two percent," says Rudy Giuliani in a new radio ad attacking Democratic plans for universal health care. "My chances of surviving prostate cancer in England? Only 44 percent, under socialized medicine.
Of course that throws the lefties into a tizzy, as it flies in the face of their theory that the government, apparently including the DMV, is more effective than private enterprise. So the uniquitous Paul Krugman weighs in.
Mr. Giuliani got his numbers from a recent article in City Journal, a publication of the conservative Manhattan Institute. The author gave no source for his numbers on five-year survival rates ¬ the probability that someone diagnosed with prostate cancer would still be alive five years after the diagnosis. And they’re just wrong. You see, the actual survival rate in Britain is 74.4 percent.
Now before we get started on the actual statistics, Krugman plays classic Krugman by himself not giving the source of his numbers. Go figure. But as the City Journal then opines, Krugman simply doesn’t understand statistical analysis chains.
Let me be very clear about why the Giuliani campaign is correct: the percentage of people diagnosed with prostate cancer who die from it is much higher in Britain than in the United States. The Organisation for Economic Co-operation and Development reports on both the incidence of prostate cancer in member nations and the number of resultant deaths. According to OECD data published in 2000, 49 Britons per 100,000 were diagnosed with prostate cancer, and 28 per 100,000 died of it. This means that 57 percent of Britons diagnosed with prostate cancer died of it; and, consequently, that just 43 percent survived. Economist John Goodman, in Lives at Risk, arrives at precisely the same conclusion: “In the United States, slightly less than one in five people diagnosed with prostate cancer dies of the disease. In the United Kingdom, 57 percent die.” None of this is surprising: in the UK, only about 40 percent of cancer patients see an oncologist, and historically, the government has been reluctant to fund new (and often better) cancer drugs.
The root of the misunderstanding is the sequence of analysis.
So why do the critics think that Britain’s survival rates are as high as America’s? The main reason is that they are citing overall mortality rates, which are indeed, as Ezra Klein writes, similar across various countries. That is, the percentage of all Americans who die from prostate cancer is similar to the percentage of all Britons who do. But this misses the point, since a much higher percentage of Americans than Britons are diagnosed with prostate cancer in the first place. If you are a patient already diagnosed with prostate cancer, like Rudy Giuliani, your chances of survival—as Giuliani correctly said—are far higher in the United States.
When looking at statistics, understanding the data population is critical. Are you analyzing the overall population or a subgroup? When comparing statistics are you comparing the same populations? Krugman is becoming famous for this error… or intentionally using it as some contend. As an aside, a comment on his own article provides another interesting statistical sidelight.
More than 70,000 Britons will have treatment abroad this year – a figure that is forecast to rise to almost 200,000 by the end of the decade. Patients needing major heart surgery, hip operations and cataracts are using the internet to book operations to be carried out thousands of miles away. Research by the Treatment Abroad website shows that Britons have travelled to 112 foreign hospitals, based in 48 countries, to find safe, affordable treatment. Yep, that the equivalent of say 350,000 U.S. citizens seeking medical care abroad… now.
Great… now I have to figure out how that plays into things… another subpopulation. Sigh…