Lady with the Lamp

Lately, I’ve been fascinated to learn about women data pioneers. Florence Nightingale was a nurse. But did you know she was also a statistician? In fact, she was the first female to be elected into the Royal Statistical Society. That’s really cool!

Flo (as I call her for short) created a way to graphically represent the cause of soldier mortality during the Crimean war (1853 -1856) by using a polar area chart.


In case it’s hard to read…

  • Red = death from wounds
  • Black = death from other
  • Blue = preventable death

Infographics weren’t really a thing back then. By presenting her data in this fun new way, she was able to quickly communicate the scale of the problem – most soldiers’ deaths weren’t from their wounds, but from preventable conditions like cholera and dysentery. The death rate went from 42% to 2% with Flo on the job!

Interesting Sidenotes:

  • The Crimean war was the first war that had media correspondence! A reporter mentioned Flo as the Lady with the Lamp which inspired the poem “Santa Filomena” by Henry Wadsworth Longfellow.
  • Flo didn’t actually invent the polar area chart, like most people think. André-Michel Guerry’s use of the polar area chart predates Flo’s. But Flo’s version, in my opinion, was much improved and better at communicating her intent. So maybe we should credit her with creating infographics!

So, I’m wondering if Flo’s polar area chart has a place in today’s visualizations. The polar area chart is similar to a pie chart. It differs in that each slice in a polar area chart has equal angles and it’s the length of the slice that varies. There’s a lot of visual best practice guides that warn against the use of pie charts. We tend to see things in length versus angles. And poking around in visualization tools like Tableau, there is no Show Me option for a polar area chart.

Does the stacked bar chart or area chart show us the same information in a more easily interpreted way? What do you think?

flo stacked bar

Found Flo’s source data and a great write-up about the math behind coxcombs at Understanding Uncertainty.

One thought on “Lady with the Lamp

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  1. This is fascinating Shanon, I had never heard of this research. Florence Nightingale’s chart is more artistic and personal, but it did take me a few minutes to understand what it was saying.

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