Alberto Cairo tells a fascinating story about John Snow, H. W. Acland, and the Mythmaking Problem:
Every human community—nations, ethnic and cultural groups, professional guilds—inevitably raises a few of its members to the status of heroes and weaves myths around them. . . . The visual display of information is no stranger to heroes and myth. In fact, being a set of disciplines with a relatively small amount of practitioners and researchers, it has generated a staggering number of heroes, perhaps as a morale-enhancing mechanism. Most of us have heard of the wonders of William Playfair’s Commercial and Political Atlas, Florence Nightingale’s coxcomb charts, Charles Joseph Minard’s Napoleon’s march diagram, and Henry Beck’s 1933 redesign of the London Underground map. . . .
Cairo’s goal, I think, is not to disparage these great pioneers of graphics but rather to put their work in perspective, recognizing the work of their excellent contemporaries.
I would like to echo Cairo’s message for a slightly different reason: I want to resist the idea that it is desirable to send a message via a single visualization. One of my big problems with graphs such as those as Nightingale and Minard is how they’re celebrated as one-stop marvels. Instead of people trying to create the next Napoleon-map, I’d prefer they graph their data and conclusions directly, using meat-and-potatoes methods such as dotplots, lineplots, and small multiples. Make the grabby viz as well—capture the excitement of the data in a graph, that’s a great thing to do—but consider that as an advertisement or intro to the data, not a substitute for direct display of the information.
By making a new graph that gets attention and engaging her audience, Florence Nightingale deserves to be a hero. But if her plots deter people from graphing and looking at the clear and direct time series, that’s a problem—not with Nightingale, but with the myth of the heroic visualization.