Edward Tufte’s The Visual Display of Quantitative Information (1998, 2nd edition 2001) is a classic book, arguably his best, and certainly a key text in the field of information graphics (which encompasses cartography). I know some cartography courses use the book as a text.
I recall being inspired by the book as a neophyte cartographer back in the late 1990s.
The book looked great: its design communicated the importance of design (when most other cartography and information graphics books were clunky and poorly designed). The tone was serious and high-minded: I was designing information graphics. And I think I absorbed Tufte’s minimalist design philosophy, although cartographic design, at least the way I learned it, was largely minimalist, with no allowance for flourish, fake 3D embellishment, or other chartjunk (or “map-crap” as I call it in the Making Maps book).
While I won’t impugn the importance of lofty inspiration, I did wonder what kind of practical guidelines I could derive from Tufte’s book. You know, specific stuff that would help me to design and make better maps. I sat down one day and made a list of Tufteisms from the book: that list is below.
20 Tufteisms from The Visual Display of Quantitative Information
- Graphical excellence is the well-designed presentation of interesting data – a matter of substance, of statistics, and of design.
- Graphical excellence consists of complex ideas communicated with clarity, precision, and efficiency.
- Graphical excellence is that which gives to the viewer the greatest number of ideas in the shortest time with the least ink in the smallest space.
- Graphical excellence is nearly always multivariate.
- Graphical excellence requires telling the truth about the data.
- The representation of numbers, as physically measured on the surface of the graphic itself, should be directly proportional to the numerical quantities represented.
- Clear, detailed, and thorough labeling should be used to defeat graphical distortion and ambiguity.
- Write out explanations of the data on the graphic itself. Label important events in the data.
- Show data variation, not design variation.
- In time-series displays of money, deflated and standardized units of monetary measurement are nearly always better than nominal units.
- The number of information-carrying (variable) dimensions depicted should not exceed the number of dimensions in the data.
- Graphics must not quote data out of context.
- Above all else, show the data.
- Maximize the data-ink ratio.
- Erase non-data-ink.
- Erase redundant data-ink.
- Revise and edit.
- Forgo chartjunk
- If the nature of the data suggests the shape of the graphic, follow that suggestion. Otherwise, move toward horizontal graphics about 50 percent wider than tall.
- The revelation of the complex.
I recall being somewhat underwhelmed at my practical how-to list. But I pondered how they related to my map making and cartography in general, and reduced them into fewer categories, the Six Commandments.
Commandment 1: Map Substantial Information, including (1), (2), (3), (4), and (20). Unfortunately, such choices were not up to me. For example, I might be told to make a map that showed the location of a dozen cities and a study area in Bolivia, and there was no way to make that interesting, multivariate, or complex. Bottom line, many maps are of boring data, chosen and assigned by someone else, and there is not much the map maker can do about it. But these five related Tufteisms did make me understand the potential for maps of non-boring data… and maybe if the clients, the people who decided what data to map, read Tufte they would do a better job at selecting interesting, multivariate, complex data to map.
Commandment 2: Don’t Lie with Maps, including (5), (6), (9), (10), (12), and (13). This evokes two classics, Huff’s How to Lie with Statistics (1954) and Monmonier’s How to Lie with Maps (1991, 2nd edition 1996). The idea of “lies” resonates deeply with some people, but it is a complicated issue. In the Making Maps book I mapped out poverty rates by county in the US, classified with different classification schemes (unclassified, quantiles, equal interval, natural breaks, and a unique scheme). This produces, of course, five quite different looking maps that, as no classification scheme is illegal or inherently “lies,” are all potentially viable. Maps are always made with a purpose, and purpose will drive the choice of classification scheme. Each scheme has advantages and disadvantages and each obscures and emphasizes different aspects of the data. Beyond the falsification of data, I find the concepts of “lies” and “truth” a bit too simplistic: it is a lot tougher than that. It’s about being smart and critical and understanding the inherent trade-offs among diverse map design options.
Commandment 3: Effectively Label Maps, including (7) & (8). This was not a revelation to me, as cartographers spent a serious amount of effort working out guidelines for the effective labeling of maps. Tufte did encourage me to include explanatory text on maps: tell people what you believe the map is showing and why it’s important. You cannot communicate everything with single words and non-text map symbols, and the map reader will see where you are coming from (and that will help them be critical of your map design choices and what you are communicating with the map).
Commandment 4: Minimize Map Crap, includes (11), (14), (15), (16), and (18). Map-crap, chart-junk, all the same: graphic dross that encrusts a map. Big, honkin’ north arrows (you don’t even need a north arrow if the orientation is obvious), fancy borders, fake 3-D effects, etc. More often map crap is the result of poor design choices for elements that need to be on the map. For example, a graticule consisting of black lines: the graticule may have to be on the map, but it should not stand out. Light gray lines, or even white lines (reversed out of a gray – as with the map that heads this posting – or colored background) would be preferable. Just like Tufte’s graph reduction exercise on pp. 126-7 in my 1st edition of The Visual Display of Quantitative Information. This minimalist design approach is stern and serious, and may be inappropriate when designing maps for advertising, promotional purposes, or fun (does anyone do that?). Chartjunk and map-crap have a place.
Commandment 5: Map Layout Matters, includes (19). Layout is a bigger issue than this one point from Tufte and it is an issue that is not stressed in map design texts (although I do devote a decent chunk of a chapter in Making Maps to map layout). It is difficult to talk about map layout (or the layout of information graphics in general) in the abstract. But layout strongly effects the look and feel of the map, and can make a map easy or difficult to read and interpret.
Commandment 6: Evaluate your Map, includes (17). Evaluation is really important and, for whatever odd reason, is typically not part of information graphics or cartography texts. There are different kinds of evaluation, from documentation of your design and production process, to formative evaluation (where you or others critique and revise your map as it is produced), and, finally, impact evaluation where formal methods are used to assess the effectiveness of the map among a subset of its intended audience. I devote parts of two chapters in Making Maps to these different kinds of evaluation.
The 20 Tufteisms and the Six Commandments are superficially less than I expected, from the perspective of practical guidelines. But, upon reflection, they do touch on many of the fundamental issues that determine if a map design is going to work or not, and what could more practical than that?