Revealing Complexity

Book: The Visual Display of Quantitative Information


Having just finished Edward Tufte’s The Visual Display of Quantitative Information, I thought I’d spend this blog post recapping some of the more interesting tidbits about making elegant data graphics.

The book ends on a powerful note as it sums up the goal of the visual display of quantitative information as such, as “the revelation of the complex.” Tufte explicitly acknowledges that data graphic designers ought not to waste their time with simple data. If the data is simple, it may be better suited to be represented as a sentence or table.

One of Tufte’s more amusing takes is his insistence on the uselessness of the pie chart as an acceptable data graphic: “A table is nearly always better than a dumb pie chart; the only worse design than a pie chart is several of them… Given their low data-density and failure to order numbers along a visual dimension , pie charts should never be used.”

The idea of data-density is itself useful and worth rehashing here. The data-density of a particular data graphic is a numerical value equal to the number of entries in the data matrix (i.e. number of observations by feature) divided by the size of the graphic. A high data-density is desirable and can be achieved by either increasing the size of the data matrix or shrinking the graphic.

Another key aspect of Tufte’s overall theory of data graphics is the idea of multifunctioning graphical elements, which is where data graphics can get quite clever and efficient. The question one wants to ask when marking something for a data graphic is: can this particular representation be used to convey more than one feature of the information to be presented? For example, Tufte notes that grid lines, often chartjunk, can actually be used as a data measure itself so in this case one should not erase gridlines. Tufte’s whole chapter on chartjunk is quite good.

Edward Tufte’s The Visual Display of Quantitative Information is, without a doubt, a must-read for any individual who works with data professionally and seriously. What’s beautiful about Tufte’s theory of data graphics is that it leaves no room for dishonesty and manipulation when showing the data, all too common today.