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
   explanation.
• 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.

Another Bad Map of Teotihuacan

The ancient Mesoamerican city Teotihuacan is the source of a contradiction that has really bothered me since I first started researching the site as an undergraduate. As one of the best-mapped ancient cities of Mesoamerica, Teotihuacan has had more bad maps published than perhaps any other Mesoamerican site. Two of the most remarkable and interesting things about the city are its great size and the large extent of central orthogonal planning of his residential neighborhoods. These features were revealed by the Teotihuacan Mapping Project starting in the 1960s, and the resulting map of Teotihuacan shows them very well (Map 1); from Millon et al. 1973.

Because of the importance of the site, Teotihuacan figures into just about any account of Mesoamerican prehistory, world prehistory, or ancient urbanism. Naturally textbook authors want to include images of the site. But why do textbook authors insist in including misleading maps of the site? For decades, pre-Teo Mapping Project maps were used in textbooks. These maps suggest that the site consists only of the main pyramids, the central street, and a few other civic buildings. I don’t have an image of these early maps handy, but most Mesoamericanists will know what I am talking about. The big problem with these maps is that they suggest that the city had lots of empty land in its central area, which is FAR from the truth. Thus they are misleading and inaccurate.

I did find a later version of this kind of map from Muriel Porter Weaver’s (1993, p. 191) textbook (see Map 2). Now this was a very good textbook, the standard before Susan Evans’ excellent text came out in 2004, and Weaver knows better. In fact, her caption reads, “Simplified map of civic-ceremonial center of Teotihuacan. Dwellings filled the spaces between constructions shown.” I guess this absolves Weaver of the charge of inaccuracy, but the map is still misleading. Why didn’t she just use the Teo Mapping Project map (Map 1 here)? I can’t answer that.

Now I find another, different, bad map of Teotihuacan in Berry (2007:211); see Map 3 here. This is quite a bad and bizarre map (compare it to the others), but then it is published in a bad and bizarre book. Brian Berry is perhaps the foremost urban and economic geographer of the 20th century, and, according to the back cover of this book, “he was for many years the world’s most frequently cited geographer.” When I saw a citation for the book, I initially got excited. I thought that Berry may have turned his analytical skills to ancient cities, which could produce some important insights. But instead it seems that after his retirement, he indulged an interest in ancient cities and self-published a non-scholarly book (no bibliography, no sources cited at all) that consists mainly of outdated information about the astronomical and ritual significance of ancient cities.

Since my undergraduate days, textbook maps of Teotihuacan have improved; many now include the map of Millon et al. instead of the misleading empty spaces maps of old. But I guess the era of bad maps is not over yet. I would guess that parallels problems could be identified for sites in other parts of the world. Although the secondary literature is always going to lag behind research findings, in this case the ignorance must have some other explanation. Perhaps publishers want simplistic maps like Maps 2 and 3 here instead of complicated maps like Map 1. I really don’t know the answer here.
Ps – I am tempted to use the example of Berry’s book to explore a couple of broader peeves I have about publishing archaeology. One is the prevalence of sloppy scholarship on the topic of cosmological significance of ancient cities. Another is the disrespecting of archaeological data and publications by scholars in other disciplines who assume that their ignorance of the archaeological record allows them to avoid citing archaeology while making up stories about the past. For the latest example of the latter, see a paper in last weeks Proceedings of the National Academy of Sciences (Basu et al. 2009).

Basu, Sudipta, John Dickhaut, Kristy Towry and Gregory Waymire (2009) Recordkeeping Alters Economic History by Promoting Reciprocity. Proceedings of the National Academy of Sciences 106:1009-1014.

Berry, Brian J. L. (2007) The World's First Cities. Private publication. Available at: www.Lulu.com

Evans, Susan T. (2004) Ancient Mexico and Central America. Thames and Hudson, New York.

Millon, René, R. Bruce Drewitt and George L. Cowgill (1973) Urbanization at Teotihuacan, Mexico, Volume 1: The Teotihuacan Map, Part 2: Maps. University of Texas Press, Austin.

Weaver, Muriel Porter (1993) The Aztecs, Maya, and Their Predecessors: Archaeology of Mesoamerica. 3rd ed. Academic Press, San Diego.