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Against the myth of the heroic visualization

hercules21[1]

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.

7 Comments

  1. Rahul says:

    In the bygone era of plots on paper and expensive color prints, was there a significantly higher premium to cramming in most info. you can onto a single plot? I wonder.

    Like those gimmicky calenders of the century etc. which are darn tricky to figure but compact nevertheless. The tradeoffs those guys made between clarity and print-space may have been different.

    Old Engineering Handbooks are full of mind boggling nomograms which are often nothing more than an ingenious way to represent a multiparameter correlation.

    • Rahul says:

      e.g. if you were a artillery man at a 1800′s siege maybe a single complex page of “infographic” that told you what elevation, charge and fuse to use for various distances, winds etc. was far easier to carry and use than, fumbling for say, 6 separate clear plots.

  2. K? O'Rourke says:

    Maybe a bit of the discrepancy is between graphs that suggest where the model may be wrong and in need of improvement (their primary role during the analysis) and ones that convince others that the model is compelling (after the analysis has been finalised).

    • Antony Unwin says:

      “Primary role”? Surely that’s not what you meant. Graphics are primarily for displaying the data, though of course they support and complement modelling too. Playfair, Nightingale, Minard all display data and have nothing to do with models. It would be beneficial if people were encouraged to use graphics more for exploring data with many displays. That will not happen if graphics are supposed to only have a role in model checking. It is also not helpful if people think their graphics always have to be innovative and gee whiz, which brings us back to the main thread of this discussion.

    • Nick Cox says:

      This distinction seems to echo that between propaganda and analytic graphs in the sense of John W. Tukey (paper in the Snedecor Festschrift 1972, available at http://www.edwardtufte.com/tufte/tukey).

      Propaganda graphs show “what has already been learned” while analytic graphs are offered in the spirit of “let us see what may be happening over and above what has already been described”.

      • K? O'Rourke says:

        Nick: Thanks for the reference!

        Antony: I use model as a synonym for representation or sign (something that stands for something to someone in some sense) and graphs are definitely such things. (I was initially trained in semiotics.)

        Now signs can be translated in innumerable ways to represent something almost the same way – my favourite graph that I made was translated in the title of the paper “Stability of treatment preferences: although most preferences do not change, most people change some of their preferences” which completely leaves out access to assessing say lack of fit (unfortunately the editor would not allow the graph in the paper).

        It’s also likely that Tukey has written on this too (I once had a short discussion with him on semiotics and it was obvious that he had a real interest in language.).

  3. Steve Sailer says:

    The classic heroic graphs work well as secret handshakes.

    When I was in the marketing research business, I had a print of Minard’s graph of Napoleon’s invasion of Russia hanging on my office wall for about ten years. Every six months or so, a stranger walking by would recognize it from reading Tufte and strike up a conversation about it with me. Out of those 20 or so individuals, every single one turned out to be somebody I was glad I met.