🌹Florence Nightingale drew polar-area diagrams of army deaths

After the Crimean War, 🏛️ Florence Nightingale published her Diagram of the Causes of Mortality in the Army in the East (1858), prepared with the statistician William Farr. Each month is a wedge measured from the centre, and its area stands for the number of deaths. Blue wedges are deaths from preventable disease, red from wounds, black from all other causes.

The blue dwarfs the red. Most of the soldiers who died in the hospitals of that war died of disease, not of battle, and the wedges shrink after the sanitary reforms of spring 1855.

Why I kept it: Adaeze Nwosu showed it to me in the break at college, on her phone, as the chart she wishes her hospital's dashboards would learn from.

So what? She did not draw the deaths. She drew two causes of death side by side, and the comparison did the persuading. That is the claim in 💎 Evidence persuades when it compares.

For my own charts: one number alone asks to be believed. Two numbers next to each other ask to be explained.