Long-time reader John S. alerted us to three charting tips given by marketing guru Seth Godin.
- One Story
- No Bar Charts
Like John, I agree with One Story most of the time. However, we don't agree completely with Seth's rationale:
If the facts demand nuance, don't use a graph, because you won't get nuance, you'll get confusion.
It is true that there are a great many confusing charts; it is even more true that more complexity leads to more confusion. The more data is plotted, the more difficult to control the message. That's why we advocate simplicity. Recently, we considered complex charts used for exploration or as catalogs. This sort of "infographics" is not intended for sales and marketing. I wonder if Seth had these in mind...
However, a well-designed chart need not cause confusion, even if it is nuanced. Gelman's chart of social and economic tendencies (here) is a great example of a nuanced chart with one main story but many subsidiary stories, if the reader chooses to look deeper.
The advice of No Bar Charts is misguided. Seth said:
The correct use of a bar chart is to show how several items change over a period of time. This, of course, demands nuance.
No, and no. If we want to show items changing over time, use a line chart. The slope of the line gives additional information, that is, the growth rate. (For example, here.) It is a tough audience indeed who consider a single time series to be "nuanced", i.e. confusing according to tip #1.
There are indeed situations where bar charts work poorly: see here. I particularly dislike grouped bar charts, much used in market research. For many such situations, line charts or dot charts do a better job.
But motion is difficult to execute well. Motion is a type of nuance, and true to Seth's words, nuance can be distracting if not done properly.
Reference: "The three laws of great graphics", Seth Godin, July 10 2008.