Enough with the bogus medical studies!

Every week, we hear about how eating such and such food gives cancer, or how working out can save you from a heart attack. If you have been reading these studies with attention and changing your life to follow their recommendations… you have been wasting your time and you have possibly harmed yourself.

Feynman famously described a common phenomenon which he called cargo-cult science. True science is a fantastic tool that has taken us, in a couple of centuries, from superstitious fools to a highly advanced civilization. Almost all major advances in the last two centuries can be linked with science. So people want to appear to be doing good science… but they are much less concerned about actually doing good science, when they even know what it is.

What is science? As Feynman wrote, it is the belief in the ignorance of experts. It is the idea that our intuition, our good sense… are not enough to tackle the world. We need objective measures. We often need mathematics. We often need hard logic. We need repeatable experiments capable of falsifying theories.

We need these things because we are easily fooled. Science acts as some sort of “software update” for the brain. You train your brain to rely on objective, verifiable facts, and hard logic… instead of impressions.

One of the core ideas behind science is that authority-based arguments should be rejected. So if Professor X from Harvard University or MIT says something… it is not scientific to believe her because she is from Harvard, or because she is a professor. It is similarly unscientific to believe something because it has appeared in a prestigious journal. It is not even scientific to believe something because of a “consensus”. (Hint: there was a widespread consensus that the aeroplane was “impossible” before the Wright brothers came along.)

Let me take this further. Believing something because impressive people say it must be so is the illustration of pre-scientific thought. And this means that every time you hear that a study by impressive people proved something new, you should doubt… you should doubt automatically, without even thinking.

How do we determine what is true? That’s one of the core lessons of the scientific revolution: it is much harder than you might expect. We are feeble creatures that very easily fall prey to bogus arguments. We must relentlessly seek incontrovertible evidence. There is no shortcut.

The real question is not how to make your mind about what is true… that is easy, your brain will eagerly accept many things as true given a chance. The hard part is to keep on doubting. We are just not wired for constant doubt, we are “believers”.

Many people do not really understand what science is… and this includes fully trained “scientists” who receive government research grants and train other scientists. What they do understand, however, is how to speak and act like a scientist. It looks like science, but it does not give the same result. That’s what Feynman calls cargo-cult science.

When it comes to medicine, we invest a lot of money in medical research. Several times more than any other type of research. Secondly, lots of real people can end up suffering needlessly if the research is wrong.

Is medical research wrong? Yes. But that’s not the most tragic part. The real problem is that much of it is pure cargo-cult science. And well funded at that. Cargo-cult science does not merely lead to the wrong ideas… it actively sets us back.

What are the problems?

  • Most work is based on observational studies

    Just watching and taking notes is not science. It is valid scholarship, as long as you report it as such. But it gets reported as “science” instead which is misleading.

    There is nothing wrong with historians who tell us that Vikings once traveled to North America. It is interesting. It is scholarship. But it is not science. It is an observation.

    Don’t get me wrong. Scholarship is precious. We know, for example, that women live longer than men. Cataloging such facts can help us… but it is not science. Our ancestors knew exactly where the stars were. They knew a lot about the seasons. Their high priests observed, cataloged… but they did not know about science.

    When you hear that exercise has been shown to reduce your risk of cancer… that’s (usually) a flat out lie. What actually happens is that scientists take a group of people. Then they ask them whether they exercise. Then they ask whether they have cancer. And then they run the statistics. “Oh! See, the people who say they exercise also less often say that they have cancer.” So far so good, but you have merely observed, you have not done any science. You have done nothing that is above what scholars routinely did in the pre-scientific era.

    All you can show with observational studies is an observation. Nothing else. It can be a lot, but it is not science.

    It could be that when Joe complains about his knee, it rains. That does not show that complaining about one’s knee brings the rain. Nor does it show that the rain brings pain to one’s knee. It is an observation, not science.

  • Small effects are greatly exagerated

    Even when scientists actually do science… they do not use the proper tools to avoid being fooled or fooling others. In fact, they often appear to seek to fool us.

    Suppose that you are treating patients for cancer. The average survival rate is 9 months. All patients die within 3 years. You give them some pill and the survival rate increases to 10 months, but all patients still die within 3 years. It is progress, but a small progress. If the pill costs 100k$ and makes you twist in pain for 3 weeks, maybe it is no progress at all.

    However, it is not how most studies will present it. They will choose a short window. Say a year. Maybe 60% of all patients die within a year. However, with the extra month offered by the pill, only 40% of all patients die within the year. Then the study will conclude that the survival rate has been increased by 50%. I kid you not.

  • They report selective effects

    Without even looking at the numbers, I can tell you that people with high-risk occupations have a lower cancer mortality. Why? Because they die younger. So, there you go… I got a cancer prevention technique: choose a high-risk occupation. Of course, this reasoning is silly. But that’s often how medical studies are presented.

  • So how to keep cancer free? You will hear things like “eating well, exercise, keeping your weight low, eating broccoli, avoiding red meat, getting tested repeatedly”. But if you actually look at the numbers, mostly, there are two factors that have an effect worth noticing on your risk of having cancer: your age and whether you smoke. Your risk of having cancer grows up exponentially with age. If eating bacon increases your cancer risk, it is by a tiny amount. What about early diagnostic? Again, a nice idea, but, in general, it is a waste of time to get regularly tested for cancer. You won’t live an extra day.

    What about heart attacks? Age and gender are basically the things you need to watch, assuming you are not smoking. Again, your risk grows up exponentially with age. Also, men are three times more likely to have a heart attack than women. Why? We don’t know. Smoking is often considered like a really bad habit. It is true that it doubles your risk of cardiovascular diseases. However, aging from 40 to 90 multiplies your risk of cardiovascular diseases by 100.

    So, how do you stay healthy? By staying young. Sadly, we don’t know how to do prevent aging. Yet.

    Demonizing hamburgers is a dangerous distraction.

    Note: I am not a medical professional. Consult your doctor if you have questions. While you are at it, ask her if she knows about cargo-cult science.

Published by

Daniel Lemire


13 thoughts on “Enough with the bogus medical studies!”

  1. This reminds me of this cartoon.

    Epidemiologists are not idiots. Yes, the science press may be misleading (and the academics may be to blame for overstating their results) but you can’t pretend that observational studies do not teach us anything. We know a lot about the harms of smoking without ever having run a RCT. Even recently SIDS has dropped by something like 75% thanks in part to recommendations like back sleeping for which there were zero RCTs:

    A smart biologist who just read news articles about CS, like this one http://www.tomshardware.com/news/zuckerman-random-number-generation-breakthrough,31821.html would conclude that computer scientists were full of baloney.

    1. This reminds me of this cartoon. https://xkcd.com/793/

      I don’t think I make the mistake of thinking that medicine is easy.


      It is true that I don’t know of an experiment where you asked some random group to smoke cigarettes while getting another random group to smoke a placebo. That does not mean that people did not run extensive scientific experiments. They certainly did. They still do. E.g., see

      Prenatal Nicotine Exposure in Rhesus Monkeys Compromises Development of Brainstem and Cardiac Monoamine Pathways Involved in Perinatal Adaptation and Sudden Infant Death Syndrome: Amelioration by Vitamin C, Neurotoxicology and Teratology 33 (2011): 431-4.

      We got just about every animal model full of tobacco and we have measured with great accuracy the results. Sure, it is conceivable that all mammals suffer from tobacco except human beings. But then, again, in science we never really prove anything, we just mount evidence.

      I agree that observational studies can serve as evidence… and my blog post says so… but you have to recognize that even if you put all the statistical wizardry into it, it is still a pre-scientific process. What it means in concrete terms is that it is unreasonably easy to derive the wrong conclusions from observational studies.

      Epidemiologists are not idiots.

      Neither are priests, historians, politicians, CEOs…

      There is plenty of poor science all over, but as my post makes clear, if there is one place where you should have robust science, it is in medical research. Firstly because they have all the money. Secondly because getting the facts wrong has dire consequences.

      1. Medical research is uniquely constrained by ethical constraints, making it hard to be “robust” in the ways we would like. For example, once we are reasonably certain that one treatment is best, it can become unethical to experiment with other treatment.

        I think that your standards would say that astronomy is not a science. After all, they just “observe” but there are no “repeatable experiments”.

        1. I think that your standards would say that astronomy is not a science.

          Observational astronomy goes way back, centuries before the scientific revolution. It is no different than geography. Please note that I qualify my statement with the adjective “observational”.

          I am pretty strong on the opinion that science requires experiments capable of falsifying theories. I am open to alternative models… yet I am not willing to throw everything into a bag and call it science.

          Medical research is uniquely constrained by ethical constraints, making it hard to be â€œrobustâ€ in the ways we would like.

          Ethics is one of many things that make medical research difficult.


          … which is an argument for putting the bar very high. It echoes a point made in my blog post about why we should hold medical research to a high scientific standard.

  2. Thanks for the article. While I agree with what you said, it would be nice to have sources for the correlation between smoking and cancer, or cardio-vascular diseases and the 100 fold increase between 40 to 90.

    1. @Pierre

      I am not going to document the link between cancer and smoking. It has been done to death. So to speak.

      The exponential growth of cancer and cardiovascular diseases with age has also been thoroughly documented, but is rarely reported in the news. Here are two plots I found after searching for 10 seconds in Google…



      You can find more. It is best if you look for yourself. It is not hard. Just use Google.

      It is a very well established fact that the risks of cancer and cardiovascular diseases go up exponentially with age.

      In fact, it is safe to say that if you were to cure aging, you’d cure cancer and cardiovascular diseases. As long as aging exists, no amount of kale and exercise is going to keep you free of these diseases (except that you may die first of something else like Alzheimer’s).

  3. In like your article. But I’d also like to add a comment:

    Observational studies are not science by themselves, but they are part of the scientific process. Hence, people doing them engage in the scientific process which is abbreviated as “doing science”.
    In that sense I find it completely legit to say “doing science” in that context.

    Of course, it’s wrong if you stop there and just write a press release. (because cargo-science)

    It’s like turning the steering wheel. Just turning it doesn’t equate to “driving a car”. But if you’re driving a car, turning the steering wheel is an essential part. And people usually would call that “driving” although at each specific point in time the driver does just turn the wheel or push some pedal or push a button or look right and left.

    I’d like to add the selection bias on so many levels in medical research. People are already not doing studies which will give a negative result. If they do a study, they might not even try to publish if the result is negative, or it just gets less effort and stays in the drawer. And if the result is negative it is then difficult to get it published, because in journals the fancy positive studies are much better received.

    In sciences like physics this is probably less of an issue, because a “negative” result is a positive result which pushes some boundary to more extreme values.ï»¿

    My 2ctï»¿

  4. I think Jon Oliver must have based last nights show on this article. Also, “Believing something because impressive people say it must be so is the illustration of pre-scientific thought.” where does this put NDT?

  5. As Peter says, observations are an important part of science. If some people didn’t publish their data, then other people wouldn’t be able to analyse it and find underlying mechanisms (which is when science really gets going).

    Respectable journals don’t allow you to publish dodgy statistics (believe me I’ve tried!) or to write conclusions that are not proven by your data. What I think you are talking about Daniel are the media reports that inflate these findings for journalistic purposes.

    1. Ok. Let us get serious here. Let me take an example…

      An international panel of experts convened by the World Health Organization concluded Monday that eating processed meat like hot dogs, ham and bacon raises the risk of colon cancer

      That’s from the New York times.

      From the WHO’s web site:

      The IARC Working Group concluded that eating processed meat causes colorectal cancer.

      Repeat after me: you can’t establish causality with observational studies.

  6. What you seem to be referring to is not “science”, but rather, the scientific method. Statistics is definitely a science. Its methods have been proven by the scientific method. The abuse of statistics seems to mostly come from people in other scientific disciplines.

    I get that drawing conclusions whole cloth from statistics is poor science. Performing tests to verify our hypothesis is using the scientific method to complete the square as it were. I absolutely agree that many, many studies are performed, even intentionally, with parameters that unduly elevate the appearance of significance when in real life, the effects are insignificant.

    Then there is an additional dimension: nowhere in the calculus of health is the quality of life measured. How many millions of people suffer feeling inadequate, feeling ugly, never happy in their own skins – just because of a number called BMI. Because Doctors masquerading as statisticians say (with very limited mathematical training) that a high BMI increases risks of this that and the other illness. Which is quite simply unproven. Real human beings, many teenagers, die of anorexia. Many more suffer their whole lives with depression, rapidly fluctuating weight (and illnesses apparently related to fluctuating weight). Then misogynistic jerks on the internet take these statistics as truth – because, you know, science, and hammer away at fat people sanctimoniously because, you know, science has given them permission to be unconscionably rude. And almost always, to women.


      That’s a great example but I don’t think it comes from doctors. BMI is used all over in research papers.

      But yes, that’s a perfect example of widespread non-science. Take a group of people. Ask them if they have cancer. Then ask for their BMI. Then say “oh! oh! people with high BMI are more likely to have cancer!”.

      That’s fine scholarship, but if you want to do science, you will have to state your hypothesis “a high BMI causes cancer”.

  7. Insightful . I am not sure how to react . This is complete intuitive natural explanation.
    Readers may get confused to think this is medical science related random writing, but this is much more then that . This specific reasoning is about how we are getting fooled.

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