Always a sucker for a good war and health related graphic, I can’t help but post about Nightingale’s Rose. The Rose is a graphical representation of William Farr’s mortality data on the Crimean War, drawn by the one and only Florence Nightingale. The chart visualizes infectious disease (in blue), battle casualties (in red), and other deaths (in black) .
While interesting, the Nightingale Rose is, for three reasons, far from my favorite visualization of casualty data. First, the wedges are measured from the center (and therefore overlap), however this is not intuitively derived from the graphic itself and thus can easily lead to misinterpretation. Second, as with pie charts, I find it difficult to accurately compare wedges of similar size. Take, for example, the August 1984 and November 1984 blue wedges. Which is larger? Third, the area of each wedge represents its numerical value, however, since this is accomplished by increases the radius of the wedge, the representation takes on an exponential property. For instance, a wedge representing twice as many deaths as another wedge would not have twice the radius. Again, this takes away from the intuitive interpretation of the graphic. Not to say it isn’t still very cool.
This graphic is republished with permission from its creator, Hugh Small.