Benjamin Todd

One of our early readers, Dr. Greg Lewis, did exactly that.

I want to study medicine because of a desire I have to help others, he wrote on his university application.

And so the chance of spending a career doing something worthwhile, I can't resist.

So we wondered, how much difference does becoming a doctor really make?

In 2012, we teamed up with Greg to find out.

Since a doctor's primary purpose is to improve health, we tried to figure out how much extra health one doctor actually adds to humanity.

We found that over the course of their career, an average doctor in the UK will enable their patients to live about an extra combined 100 years of healthy life, either by extending their lifespans or by improving their overall health.

There is, of course, a huge amount of uncertainty in this figure, but the real figure is unlikely to be more than 10 times higher.

Using a standard conversion rate, used by the World Bank among other institutions, of 30 extra years of healthy life to one life saved, 100 years of healthy life is equivalent to about 3 lives saved.

This is clearly a significant impact, however it's less of an impact than many people expect doctors to have over their entire career.

There are three main reasons this impact is lower than you might expect.

1.

Researchers largely agree that medicine has only increased average life expectancy by a few years.

Most gains in life expectancy over the last 100 years have instead occurred due to better nutrition, improved sanitation, increased wealth, and other factors.

2.

Doctors are only one part of the medical system, which also relies on nurses and hospital staff, as well as overhead and equipment.

The impact of medical interventions is shared between all of these elements.

And three, most importantly, there are already a lot of doctors in the developed world, so if you don't become a doctor, somebody else will be available to perform the most critical procedures.

Additional doctors therefore only enable us to carry out procedures that deliver less significant and less certain results.

The last point is illustrated by the chart below, which compares the impact of doctors in different countries.