Nobel By Chocolate
    By Johannes Koelman | October 13th 2012 10:50 AM | 7 comments | Print | E-mail | Track Comments
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    Winston Churchill liked his chocolate and he liked it rich and dark. At least that is what Hitler must have been convinced of as he decided to lure the British prime minister not with cigars but with dark chocolate. Churchill barely escaped his death by chocolate and went on to win the Nobel Prize in literature.


    According to New York cardiologist Dr. Franz Messerli: maybe not. Messerli dares to ask the question "How much chocolate does it take to win a Nobel?" and does not shy away from providing us with an answer.

    No kidding. We are talking research reported in the most prestigious peer-reviewed medical journal in the world. A journal that amongst all scientific journals in the world ranks number three in terms of impact factor, just behind Nature and Science. Evidently, this is serious stuff we can't brush away as yet-another-fun-correlation-to-make-you-smile. Have a look yourself.

    Where to start?

    You don't need any degree in medicine to see this article makes more than some occasional errors. Frankly, I wonder how this rubbish could go viral in the popular media (Time, Reuters and Forbes) without anyone pointing out its many flaws? And more importantly: what on earth caused the editors of the New England Journal of Medicine to accept and publish this paper?

    I reproduce the plot that forms the core of Messerli's article:

    Messerli writes:
    "There was a close, significant linear correlation (r=0.791, P<0.0001) between chocolate consumption per capita and the number of Nobel laureates per 10 million persons in a total of 23 countries [..] The only possible outlier in the figure seems to be Sweden."
    Say what? Only possible outlier? What about Germany? What about Brazil? Messerli cleverly avoids putting into the figure the trend line he is advocating. I can guarantee you that whatever regression line he would put in, Brazil's chocolate consumption is about an order of magnitude too large compared to its Nobel Prize count. The same applies, albeit to a somewhat lesser degree, to Germany, Spain and China.

    But ok, I can forgive Messerli his overly optimistic description of the outlier statistics, would that be his only error. But it isn't. In fact, his conclusions go completely astray due to a loose handling of units. Messerli writes:
    "The slope of the regression line allows us to estimate that it would take about 0.4 kg of chocolate per capita per year to increase the number of Nobel laureates in a given country by 1."
    This is patent nonsense. Maybe Messerli means to say "it would take about 0.4 kg of chocolate per capita per year to increase the number of Nobel laureates per 10 million inhabitants by 1". But even that would be incorrect. The problem is caused by a sloppy use of units. The point is that the vertical axis in Messerli's plot shows the total historical number of Nobel laureates per 10 million capita. Would someone make the same plot say ten years into the future, all the data as well as the regression line will shift, simply because the total number of Nobel prizes will have increased by then.

    This problem can be avoided by properly normalizing the quantity displayed on the vertical axis. In fact, one can argue that Messerli is effectively plotting the number of Nobel laureates per century and per 10 million inhabitants. So the correlation Messerli derives is not "0.4 kg per capita per year per Nobel" but rather "(0.4 kg/year/capita)/(Nobels/century/10 million capita)".

    In other words: 400 million kg of chocolate would correlate with one Nobel prize. This goes against Messerli's conclusion that to increase the Nobel count by one "for the United States, that would amount to 125 million kg per year".

    Messerli's worst sin, however, is not his sloppy use of units. The most astonishing error stares us in the face when in the article he brushes aside a common cause between chocolate consumption and Nobel prizes:
    "it is difficult to identify a plausible common denominator that could possibly drive both chocolate consumption and the number of Nobel laureates over many years. Differences in socioeconomic status from country to country and geographic and climatic factors may play some role, but they fall short of fully explaining the close correlation observed"
    and concludes that a causal relationship between the consumption of chocolate and cognitive capabilities is the likely explanation for the observed correlation:
    "it seems most likely that in a dose-dependent way, chocolate intake provides the abundant fertile ground needed for the sprouting of Nobel laureates"
    That takes the biscuit.

    Dear Dr Messerli and dear editors of the New England Journal of Medicine, may I suggest that a country that spends more on chocolate might perhaps also be capable of spending more on education? Just my two cents.


    When I first saw the title of this post I thought 'here we go again' (my facebook feed has been bombarded with people referencing this study the past few days)....but then I was pleasantly surprised that someone (who has a better understanding of statistics than I do, ha) finally took the time to point out how ridiculous that article is. I  can't understand how/why it got published in the first place...
    The chocolate-Nobel connection is even better than the strong positive correlation between the shoe size of elementary school children and their knowledge of arithmetic.
    This is outstanding. At least BMJ does its prank articles at the same time every year, so they are easier to spot.  I haven't chuckled this much since Journal of the American Chemical Society published 'Evidence for the Likely Origin of Homochirality in Amino Acids, Sugars, and Nucleosides on Prebiotic Earth', in which the author concluded dinosaurs could be ruling on other planets.
    Thor Russell
    "I wonder how this rubbish could go viral in the popular media (Time, Reuters and Forbes) without anyone pointing out its many flaws?"

    It went viral because its flaws are so obvious that the general public can immediately see them. People feel special if they read rubbish science, it makes them feel smarter. Newspapers that report such studies are guaranteed clicks.
    Thor Russell
    Ashwani Kumar
    Will someone correlate it  with per capita income of a country and Nobel awards ? or Chocolate is enough ?
    I would like some brave soul to plot distance from the equator vs density of Nobel prizes. I think that it would show an even greater correlation. You know, with the Nobel laureates being predominantly Scandinavian and all. At least we would certainly remove the outlying Brazil, albeit Austria might now come out a bit too strong on the Nobel side...

    The most likely scenario is that Franz Messerli, a professor of medicine and the Director of the Hypertension Program at St. Luke’s-Roosevelt Hospital in New York, wrote the paper as response to "Chocolate consumption and cardiometabolic disorders" (BMJ, v343:d4488, 26 Aug 2012) with the intention of showing that one can show significant correlations between almost anything. You see this especially in the social sciences, the Richard Florida new ubanist correlations cited by city planners to justify all sorts of fantasies.

    Without reading the original article (something the Hammock Physicist does not appear to have done either) one can't be certain of that but given the research focus of Dr. Messerli, the number of publications he's (co)authored and the high quality of the medical journals they are published in, that is a lot more plausible than the stance of this blog entry.