Why are medical doctors expected, or required, to be good at math?

I long ago heard a lawyer joke, “If I were any good at math, I’d be a doctor.” I certainly understand doctors being required to master various sciences such as biology, chemistry, anatomy and even botany, which have a direct impact on understanding what they do and the medical care they provide, but why math? Other than maybe figuring out the right dose of prescription medicine (which could probably be done by calculator these days anyway), is it really necessary for a good doctor to be good at math?

At a minimum I would expect doctors to be able to use and understand statistics since that is how most medical stuff is reported.

Are they?

I don’t recall the pre-med track at college requiring any math beyond what would be typically expected of a natural sciences major. And I believe most medical schools would only require 1 or 2 semesters of college math. That’s far above the average bear but not particularly special as college graduates go.

Even acing those classes wouldn’t be considered “good at math” by the standards of most, say, engineers.

Mistakes happen, even if you use a calculator. Being good at math makes you better at noticing those. That doesn’t require any extra college courses in math though.

Because you need math skills to master biology, chemistry, anatomy, etc.

Most doctors are good, but not great, at math.

Generally, you need good marks to get in and this generally includes a university calculus course, physics and chemistry.

As a doctor, you might need to understand how to use formulae to calculate (for example) drug doses, kidney function, basic statistics, prevalence, sensitivity, odds ratios, metabolic and respiratory acidoses, anion gaps, radiation doses, cardiac function, toxicity etc. but in practice math is much more important in medical research or interpreting studies than it is in daily practice (with some exceptions).

Doctors often have a very basic understanding of law and the reverse may or may not be true.

I studied Engineering and tutored Medical Students and did curriculum development for Technical Officers. Half of my family are medical doctors, I’ve worked in medical systems, and read medicine for interest for decades.

In our system, (Australia) high school students who wish to become doctors study math at high school because it is a difficult subject that requires no understanding, that you can master just by studying. Apart from the fact that ‘just studying’ is the most important skill for medical students, the math they study has very little relevance to medical studies (it does lead directly into engineering math). In their university studies, they have to cover an enormous amount of material, a tiny amount of which is math, which they never take to a level beyond what a typical Engineering student or Math student would do in first year.

If they wish to understand statistics, they study independently (medical students and doctors are really good at studying).

If you wanted to be a Doctor, you would do math at high school.

As others have said, you need math “to get in”. There are class requirements you need that require math. You also have tests to pass to get in, which may call somewhat on these math skills. Some degree of math is shorthand for “smart enough to learn hard stuff and figure things out”.

(Actually, the key skills you need in medical school and residency are:
-the ability to take in a lot of knowledge quickly, that is “drink from a firehose”, and retain most of it,
-the ability to just keep going when you’d rather stop, and
-the ability to do good work when tired.)

There is some math in medical school, some of which goes to learning basic stuff well enough so that it sits in the background, informing other stuff, but rarely thought of directly.

In the clinics, math is mostly arithmetic or ratios, or even simply adding up points on some clinical scale you are using. (Doctors have to know a LOT of numbers, normal values and ranges, or what size this can get to before it needs to be fixed, etc- that’s not really math.) Of course, nowadays, calculators and computers are doing most of what passed for math that we might have done previously. I have many, many links to websites that do various medical calculations.

Statistics are very math relevant, and remain important after training. Most of us understand statistics much better than the average citizen, but we’re not mostly super at it. Leaving out doctors who DO research, most of us are worse than the average scientist. Even many doctors who do research have statisticians to help decide how to do the statistics.

@Blue_Blistering_Barnacle - thank you for the nice write up. I had a follow up question on units. In the engineering world, we have to do a lot of unit conversions when dealing with different countries/conventions.

How’s it in the medical world ? Is there an effort in the medical world to use consistent units ? Some examples that come to mind :

Dosage per lb or kg , dosage in mg or oz, temperature in C or F, Blood pressure in mm Hg, etc etc

I’m an engineer who has a master’s in (applied) math. I know plenty of doctors. Some of them are what I would call good at math, but a lot really sweated it during undergrad.

As blue_blistering_barnacle notes, doctors are required to be really good at lots of things. Being good at math will make some of those things easier.

I hear the joke as more of a standard putdown of lawyers–if the lawyer were good enough at math to pass undergrad science, he would have obtained a more elite credential, instead of going the bluster/crookery route.

Units can be a problem in medicine because the metric world often uses different measurements than the United States. It’s not a huge problem - you need to be aware there are sometimes well known differences and look up the conversion factor.

Thanks, all.

Does medicine ever use anything other than the metric system in the US since…I dunno…many decades?

There is one specialty I know of where math skills are important: ophthalmology. If you have cataract surgery, docs need to do calculations that include the surface and curvature of the cornea as well as the level of myopia, etc. to determine the exact measurements of the IOL (intra-ocular lens) they need to insert.

I base this on my own experience so decided I’d better look it up, too.

Few subjects in the field of ophthalmology are as complex as the formulas surgeons use to predict the best intraocular lens power for a given patient. As at least one expert has noted, creating and improving upon these formulas is a job best managed with the help of physicists, mathematicians and optical engineers. Nevertheless, these formulas are an essential part of performing cataract surgery.

My situation was pretty complex, so I’m glad my surgeon was good at math.

If the system where you are is anything like Canada, you need to do 2 or 3 years of certain sciences to get admitted to medical school. (Typically biology and chemistry) and many (all?) universities require that to take these courses, you be enrolled in a majors program that involves them; and any such programs will also include mid-level math. That is, not necessarily the math that physicists or engineers need, but understanding algebra, calculus, statistics, etc. Plus, since your marks in your pre-med classes are very relevant to admission, you better do pretty good in those classes.

The US conventions are a little different. An average blood glucose in Canada might be 5.5 mM/L. In the US, glucose is measured in mg/dL. This example is metric, but you still need to multiply by the molecular weight of glucose (180.16 mg/mM divided by 10dL/L; about 18). Canadians prefer hemoglobin to hematocrit. There are many other examples.

As someone who has trained medical students and medical residents for decades, I would not say that many are “good at math”. They are usually competent in “math”, but almost to a person they have been utterly dependent on apps for even the simplest numerical calculations.

I should also say (as a previous math major turned physician) that there is precious little math in real-world medicine. Sure, there’s lots of arithmetic, but math? Not much.

On the other hand, understanding and applying many key physiologic concepts (e.g. hemodynamics, ventilation/perfusion, renal filtration) to the practice of Internal Medicine and its subspecialties requires a mode of thinking (a mental model) that I would say is fundamentally mathematical.

I concur.

Frank Abagnale, Jr.: Dr. Harris, do you concur?

C’mon - I can’t begin to tell you how many times I’ve been bailed out of tough situations by my knowledge of calculus and trigonometry.


A working knowledge of statistics is helpful in evaluating the medical literature, but even MD/PhD researchers may depend on the expertise of trained statisticians.

I’d lay odds* that a computer was used to make those calculations and that your surgeon didn’t decide mid operation that he had to finish the procedure by dead- reckoning.

  • ‘cepting I don’t know my figgerin’ well enough to quite know the odds!