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Nightingale Rose Chart
Also known as: Coxcomb Chart, Polar Area Diagram.
This chart was famously used by statistician and medical reformer, Florence Nightingale to communicate the avoidable deaths of soldiers during the Crimean war.
Nightingale Rose Charts are drawn on a polar coordinate system. Each category or interval in data is divided into equal segments on the radial chart. How far each segment extends from the center, in proportion to the value it represents, depends on a polar axis. So each ring from the center of the polar grid can be used as a scale to plot the segment size and represent a higher value. Therefore, it's important to notice with Nightingale Rose Charts that it's the area, rather then the radius of a segment that represents its value.
The major flaw with Nightingale Rose Charts, are that outer segments are given more emphasis because of their larger area size. This disproportionately represents increases in value.
Data over time