I am a mathematician, not a physician. I hold a PhD in mathematics from UC Berkeley and retired as an IBM Distinguished Engineer, after decades applying mathematical reasoning to a variety of fields. This newsletter grew out of a course I developed with Joel Keenan, MD.
Medical information arrives every day. Headlines, drug advertisements, guidelines, test results, diagnoses. Most of it is harder to read than it looks. This newsletter exists to help you read it.
There will be three kinds of postings.
• The everyday recommendations, such as BMI ranges and blood pressure targets.
• The large public arguments, such as the one over vaccines.
• New claims as they surface online, taken up while people are still talking about them.
When I applied my mathematical training to the medical claims reaching the public, I found that the numbers are usually computed correctly. What breaks is the reasoning wrapped around the numbers, and it breaks in the same six ways. I call them faults, and each has a plain question that exposes it.
· Relative reporting. What does a 36% improvement from taking a drug really mean?
· Probability reversal. Does a positive COVID test mean I have it? Does a negative mean I’m not contagious?
· Arbitrary categories. How concerned should you be if your systolic blood pressure goes from 119 to 120?
· The Bernoulli fallacy. Why does the published medical advice keep changing?
· The causal leap. Does bird watching prevent dementia?
· The syndrome trap. If two people have the same diagnosis, what do they actually have in common?
There is a short paper on each at healthy-skepticism.com, free to read and share.
The goal is not to make you distrust medicine. The progress is real. The goal is a better conversation with the people who treat you.
Nothing here is medical advice. Decisions about your care belong to you and your doctor.
If a claim is puzzling you, send me an email. I read every
Murray Cantor PhD