Friday, February 1, 2013

Edward Tufte and graphics

Minard's map of Napoleon's Moscow campaign
I attended a day-long workshop today run by Edward Tufte. If you aren't familiar with his books and ideas, you should be. Tufte is a statistician/political scientist retired from Yale University who has published four books on how to present information--particularly quantitative data--in graphical format. He frequently refers to the figured map produced by Charles Joseph Minard in 1869 showing the fate of Napoleon's Moscow campaign of 1812 (see above). To Tufte, this is the finest informational graphic ever published. It presents reliable data in an easily comprehensible, but rigorous format. Napoleon's army left the Polish-Russian border (left on the diagram) with 422,000 soldiers. By the time they got to Moscow (right side), following the tan shaped route, the army was much reduced through attrition due to freezing and starvation. Their retreat is shown in black; when they got back to the border the army was down to 10,000. There is a graph of temperature along the bottom, showing the below-freezing temperatures at several points along the retreat.

Here are Tufte's books:

Tufte, Edward R.
1990    Envisioning Information. Graphics Press, Cheshire, CT.

1997    Visual Explanations: Images and Quantities, Evidence and Narrative. Graphics Press, Cheshire, CT.

2001    The Visual Display of Quantitative Information. 2nd ed. Graphics Press, Cheshire, CT.

2006    Beautiful Evidence. Graphics Press, Cheshire, CT.

His basic book, The Visual Display of Quantitative Information, was first published in the early 1980s. Each book adds new examples and new perspectives on visual presentations. The latest one, Beautiful Evidence is the most synthetic and theoretical. Tufte spent some time in the workshop today on the material in the chapter, "The Fundamental Principles of Analytical Design." His basic notion is that fundamental principles of analytical thinking translate directly into the principles of good design. He even quote Durkheim in this section. Here are the basic principles:

  • Comparisons: A graphic should show comparisons, contrasts, and differences.
    • The Minard map compares the two legs of the campaign, and it also compares the army's progress and army size with temperature data.
  • Causality, Mechanism, Structure, Explanation: A graphic should illustrate causality.
    • Tufte suggests that Minard's maps is thin on causality, not going beyond the temperature
  • Multivariate Analysis: A graphic should show many variables.
    • Minard's map shows latitude and longitude, army size, the size of the army, the chronology of the campaign, and temperature.
  • Integration of Evidence: graphics should combine "words, numbers, images, and diagrams" in clear and explanatory ways.
    • Minard's map nicely integrates the graphical and textual.
  • Documentation: A graphic should establish its credibilty by citing sources and using other mechanics of scholarly documentation and rigor.
    • Not surprisingly, Minard cities his data sources clearly, provides his own name, etc.
  • Content Counts Most of All: A graphic should be tailored to present the basic information or ideas of interest. The form of the graphic is less important than its content. 
    • Minard did not set out to produce a jazzy graphic, bur rather to illustrate starkly the horrors of war.
You shouldn't have much trouble relating these six principles to archaeological graphics. More attention to Tufte's principles would improve not only the aesthetics of archaeological graphics, but they would improve our analytical thinking and communication.

Beautiful Evidence includes Tufte's iconic essay "The Cognitive Style of Powerpoint" (a strong critique of powerpoint). Here is a quote from one of his books: "The only thing worse than a pie chart is multiple pie charts." Thanks to the workshop, I now own all four books, and I've read a number of chapters. This is really great stuff, and well worth a look.

Check out Edward Tufte's website for more information. It even has some information on Richard Feynman, one of  my heroes.

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