We bring attention to a book on graphics written by Bernard Lebelle, a frequent contributor to this blog. The book came out in France earlier this year. The title is "Convaincre avec des graphiques efficaces sous Excel, PowerPoint ...", published by Eyrolles. Thankfully because much of the book is visual, I don't need to know French to understand much of it. Here, I discuss two interesting things:
On page 13, he discussed flow diagrams using the energy flow example that led to a long discussion on this blog. He proposed using a Merimecko chart instead.
On page 89, he showed a concentric circle chart (see below). This is a relatively simple train schedule showing the frequency of trains at each hour on each day of the week. It looks interesting because of the allusion to the clock, except that typical clocks have twelve hours rather than 24. I'd create a set of two charts, one for the first twelve hours, one for the second twelve.
This sort of chart is very limited in utility but it works well here because the data is entirely categorical - one or two trains per hour, hour of day, day of week - and in addition, the relationships are very simple. In fact, the reader/user does not need to read any trends, general patterns or estimate the size or shape of anything. The user is performing a simple search operation, that's it.
(The innermost circle is unlabelled so it is unclear what that signifies.)
Lebelle provided an alternative on page 90, which is essentially a data table, with time on the vertical dimension and calendar date on the horizontal, and the frequency inside the cells. This is more straightforward, less interesting.
On page 151, he mentioned the self-sufficiency test that we discussed often here. A graph should do more than just print all the data in the data set.
Lebelle is currently Senior Manager at Deloitte, the management consulting company, and he focuses on graphical construction in Excel. This is both a limitation and an advantage. Excel, of course, has many imperfections (don't get me started on the new and horrid Excel). However, Excel is still the most widely used graphing application, by fa
The book takes a perspective on charting that fits our philosophy very well. Here is a rough summary of the contents of the book (any mistakes are mine):
chapter 1: a summary of the key features of good charts... issues such as clarity and efficiency of the message are addressed
chapter 2: historical perspective, with examples from Playfair, Minard, Nightingale, etc. page 38 has an interesting table comparing the contributions of Bertin, Tukey, Tufte, Ware and Cleveland.
chapter 3: constructs of a chart such as axes, legends, etc. page 43 explains the difference between "information design", "infographics", "charts" and "information visualization". introduces chartjunk, data-ink ratio.
chapter 4: "decoding" of a chart. Discusses optical illusions, which I also consider to be fundamental to understanding the effect of charts on the audience. Talks about how different ways of displaying the same data is perceived differently. Interesting section (starting p.101) considering some quantitative theories about perception, citing Ernst Weber and Stanley Smith Stevens.
chapter 5: process of making a chart. The nitty-gritty things like transforming the data, picking a scale, etc.
chapter 6: examples. Also introduces a classification system for charts. It has one of those flowcharts which is supposed to allow someone to pick a type of chart based on whether the data is numeric or categorical, etc. I know this is very popular in engineering and scientific textbooks but I have never found any use for such flowcharts. There are 30 - 40 pages of charts here and a great resource to get some ideas.
chapter 7: exercises
chapter 8: resources