The visual display of scientific information – is it accessible?

During the Washington D.C. water crisis, the Center for Disease Control (CDC) conducted a study purportedly to examine if there was any harm done to the public between 2001 and 2004. The study concluded that no harm occurred. After listening and talking to Dr. Simoni Triantafyllidou about her work on the same study objective as the CDC study, it becomes readily apparent that data manipulation is a key factor in the visualization of study outcomes. The CDC study lumped all blood lead levels (BLL) into a single data category whereas Dr. Triantafyllidou isolated the BLLs by high risk and low risks populations. This simple adjustment to the data set yielded significantly different visual results.  By combining the data set, CDC softened the curve and generated like results as previous years. Their conclusion that this like result demonstrated no risk is just bad analysis but it wasn’t obvious from just looking at their graphic. An increased risk was demonstrated by the CDC study because they showed the Washington D.C. data as a shift above the national trend line.   Dr. Triantafyllidou adjusted the picture to amplify that shift and wrote a different story line.

Edward Tufte has written several books on the visual display of quantitative information. Graphics reveal data and are instruments of communication and in this way, “data graphics are no different from words, [and] any means of communication can be used to deceive” (Tufte, 2001, 53). Tufte points out that when people are presented with visual information, they, “quickly and naturally” direct their attention, “toward exploring the substantive content of the data rather than toward questions of methodology and technique” (ibid., 20). “Our visual impression of the data is entangled,” in the ideologies of the producer and consumer of the graphic (ibid.).

In the same way a scientist or an engineer can harness authority just by their stated profession, a scientific graphic can harness authority because it looks like a fact. In the spirit of increased community participation in science, a sharedness of meaning must occur. How can complexity become more accessible? Most scientific or engineering graphics do not do this well. “Imagine if graphics were replaced by paragraphs of words and those paragraphs scattered over the pages out of sequence with the rest of the text [or meaning] – that is how graphical and tabular information is now treated in the layout of many published pages, particularly in scientific journals and professional books” (ibid., 181).

Tufte recommends some techniques in graphic display which might help. Words, graphics, and pictures should be combined in the display of information. Segregation of meaning between the words and the graphics should always be avoided. Specifically, in graphics in exploratory data analysis (as in BLL over time box charts), “words should tell the viewer how to read the design and not what to read in terms of content” (ibid., 182). The art and creativity of science lies in taking the data or facts and determining a finding. And citizens impacted by the risk a scientist or engineer may be studying, have a right to see the data and draw their own conclusions.

 

Tufte, Edward R. (2001). The Visual Display of Quantitative Information. Cheshire, CN: Graphics Press.

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4 Replies to “The visual display of scientific information – is it accessible?”

  1. Very interesting observations. There certainly is power in the visual display of scientific information and, as Tufte points out, this power often places readers in the perhaps intimidating position of trying to “decode” the message rather than asking questions about methodology and technique. The problem, of course, with the CDC/DOH study was not limited to the visual display of the findings, but I think one could argue that the visual display of the findings lended the study a greater degree of scientific authority.

    What I think is worth noting about the CDC/DOH study is that once it was published, it received no challenge whatsoever from the medical, public health, or environmental health communities that purport to have expertise on a) lead and childhood lead poisoning and b) science. The only people I am aware of who had no involvement in the study’s creation and who knew the study was false were DC parents who had established independently that their children had been poisoned from the water. Marc Edwards too, quite early on, knew something had gone wrong with this study, if only because the study’s conclusions contradicted decades of prior scientific research as well as common sense.

  2. I’m one of many engineers who became aware of Edward Tufte as a result of his critique of NASA’s internal communications in the Columbia Accident Investigation Board’s report. Part of his point was that engineers who did NOT want to conceal data were very capable of losing their point and accidentally misleading their audience with a poorly constructed figure. If key facts can be accidentally hidden, does training engineers better in communications run the risk of making them just more skillful at hiding what they do not wish to share?

    1. Only if they intend to be unethical. I don’t assume scientists and engineers start from a point of unethical. If they move in that direction – why? what were the incentives?

    2. I don’t know that the engineers did not intend to conceal data. At least in the case of the vendors who built the shuttle, they had an incentive to conceal data in order to shift blame and minimize their own liability in the accident. Intentional or not, visual displays are powerful especially if they depict exactly what the consumer wants. Another Tufte tidbit I took away from attending one of his workshops: “absence of evidence is not evidence of absence.” There is a temptation to stop or be satisfied once you get the answer you want instead of looking further to get to the truth of the matter.

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