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Cancer clusters — 9 Comments

  1. This is one of the cases where common sense expectation (intuition) and mathematics tell us two different stories. Just make a random distribution of dots on a square, by using random number generator for X and Y coordinates. You will immediately see some clasters, that is, places where density of dots is higher then average. Our perception works remarkably well in detecting any regularities or anomalies. Moreover, if you do not see any clasters this means that dots distribution is, in fact, non-random: there should be some anti-correlation, repulsion of dots from each other. Only test on statistical significance can tell us whether these apparent clasters are simply random density fluctuations, inevitable for true random distribution. And yes, this is always hard to explain to people without mathematical training.

  2. Repeat over and over until it internalizes: Correlation does not imply causation. Really, if you simply remember that *one* sentence from a statistics course you will note that a VERY large number of “studies” are bogus.

    South Park had a funny episode called “Medicinal Fried Chicken”. Colorado passed a law barring fast food from low income areas (apparently they were actually discussing doing this for our improved health) and a medicinal marijuana moved into the old KFC that was removed because of the law. A number of the residents figured out if they gave themselves cancer they could get legal marijuana and they all did so.

    In the end a study found that where the KFC’s were replaced by medicinal marijuana places that the testicular cancer rate (the one chosen by the male residents) shot through the roof. Therefore one could only conclude that fried chicken has a miraculous medicinal property to prevent testicular cancer.

    A great deal of these studies are just as good as that one, it is just they play on fears the public has so few think they are stupid, yet they truly have the same amount of religious methodology. Small sample size, correlation means causation, and an unwillingness to explore anything other than the outcome the researchers wanted couple to make a horrid report and equally horrid policies based on it.

  3. When my son was diagnosed with leukemia, we were pretty quickly made aware of various other cancer diagnoses in the neighborhood. My wife and I had many discussions about possible environmental causes, because as parents the need to find a REASON was overwhelming. In the end we decided that it didn’t make sense. After much study we concluded that we simply couldn’t pick a cause or source for the disease. Now many years later and more than a few stats courses, I still think that’s the right answer. No clear causality, which does not generate a comforting narrative, but I prefer that to a fairy tale.

  4. This is similar to how global warming has people pointing out wild and whacky weather. Strictly a problem in understanding average is not the same as normal. Averages are compiled out of whacky which is still in the category of normal. What would be abnormal is if whacky no longer occured.

  5. Lots of adult cancer patients about to embark on treatment asked me about causality. It was always an early question, pre-empting the discussion of treatment options, toxicities, outcomes, etc. My reply started along the lines of, “When your house is on fire, do you ask the firemen as they show up, ‘What caused it? How did it start?’ ”

    If we could assign a cause to each case of cancer, how would that give comfort? To tell a young woman, non-smoker, non-drinker, with oral cancer that it is most probably viral-induced will comfort or help her how, as she faces possibly deforming surgery and radiation therapy?

    Are we hung up on cause and effect in other realms? Are Obama’s actions foolish or the result of knavery? I get no comfort or satisfaction one way or the other. Like cancer, I don’t care about the cause; I want to stop him any way we can.

  6. Cancer is not a single disease, but hundreds of different diseases with very different ethiology. Some are quite common, some are exceptionally rare. Sarcoma Kaposhi, for example, was so rare that most GP never seen it in their practice, untill epidemic of it occured in San-Francisko gay community; that is how HIV virus was discovered, by a sudden claster of a very rare cancer.

  7. People hate to think they have no control. Randomnity sucks.
    Having control requires power over the issue, which first means knowing a cause. Then the cause can be addressed, or at least blamed.
    And, while correlation does not equal causation, it does require explainin’
    All same-same vaccination nuttiness.

  8. I’m impressed that the New Yorker published the Atul Gawande article. After all, it put the powerline/cancer myth on the map with an article by Paul Brodeur in 1990. I wonder if they ever published a retraction? Two magazines in one, as James Taranto is fond of writing.

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