Chart Types

In The three laws of great graphs, Seth Godin gave these three laws for great graphs:

1. One Story
2. No Bar Charts
3. Motion

In Bar graphs vs. Pie charts, Seth further explains his comments about bar charts:

[T]he purpose of a chart or graph is to make one point, vividly.

I commented on Seth’s three laws in Seth’s Three Laws of Great Graphs, where I agreed in principle with rules 1 and 3. I felt he was overly dismissive of bar charts and overly permissive of pie charts, and suggested an alternate rule 2: Choose Chart Types Intelligently. I countered Seth’s criticism of bar charts in Bar graphs vs. Pie charts, by showing examples of bar charts which were improvements over the pie chart he gave as his example.

Two of my favorite bloggers have joined the debate about Seth’s charting guidelines:

• Seth Godin on Great Graphs: A Very Light Purple Cow by Jorge Camoes of Charts
• Seth Godin on charts by Kaiser Fung of Junk Charts

Jorge says that Seth’s One Story rule should really say tell a story clearly, which also means include necessary information but leave out irrelevant information. Jorge agrees with me that Seth’s “No bar charts” rule is misguided, and should be a more thoughtful process of choosing the right chart type. Jorge feels that motion can play a part in effective information display, but that Seth’s motion is “just a silly dramatic effect for presentation purposes”. Finally, Jorge presents his own three rules:

1. Tell a story;
2. Remove irrelevant data;
3. Choose the right messenger;
4. Bonus law: let the user write the story.

Kaiser agrees with Seth’s One Story rule, but not with the idea that nuance is bad and leads to confusion. A better guideline than reducing nuance is reducing complexity through careful planning and design. Kaiser feels that Seth’s prohibition of bar charts is based on an unfamiliarity with which chart types best depict which types of information. Kaiser shows some bar charts which are not well designed, but agrees that bar charts are valid in many cases, and other types beside pie charts may also be effective.

In fairness to Seth Godin’s point of view, he is talking about making marketing presentations to nontechnical audiences, and you often need to make a quick point without confusion or distraction. My own background is in making presentations and writing reports for highly technical audiences of scientists and engineers, people who live with numbers. It is still important to provide a clear statement without extraneous detail, and for this crowd, extraneous detail has a different definition. But when I think about removing nuance from charts, I am reminded of Jack Nicholson’s famous “You can’t handle the truth!” tirade from A Few Good Men.

Update (14 July 2008)

Three more favorite blogs of mine have chimed in, with commentary much as I have described above:

• Chart Rules, As Simple as Possible, But Not Any Simpler!, in More Information per Pixel!
• Godin Dumps on Bar Charts; Data Visualization Record Falls to 1 and 1, by Zach Gemignani, Juice Analytics
• Godin’s Silly Rules for Great Graphs, by Stephen Few, Perceptual Edge

Update (15 July 2008)

Several additional reviews have come to my attention:

• Three laws of Great Graphs?, by Geoff Urland, Corona Research
  Geoff went along with the “conventional wisdom” above.
• PowerPoint, Presentations, and Speechmaking, by Laura Lee Dooley of Dooley Online
  Laura said simply “These are great guidelines” then proceeded to provide more PowerPoint guidance.
• Marketing and Charts, by Brett on Market Anomolies
  Brett said Seth’s post “is a must read”.

Apparently there is quite an industry surrounding the wisdom of Seth Godin. A lot of his marketing advice seems very well founded. I’ve seen him on YouTube, of course, but I didn’t understand the magnitude of his following. If you Google for Seth, you will find dozens of blog entries by people who only link to his posts, or reiterate the takeaways from his posts and say “Good stuff” and “Seth’s done it again!” The proportion of readers who step back and say, “Seth’s pretty smart, but I don’t think that’s right” seems pretty small.

The three laws of great graphs contains Seth Godin’s guidelines for charts used in presentations:

1. One Story
2. No Bar Charts
3. Motion

In Seth’s Three Laws of Great Graphs, I agreed in principle, but suggested changing item 2 to “Choose Chart Types Intelligently”, because bar charts are not intrinsically worse than any other chart type.

In Bar graphs vs. Pie charts, Seth further explains his comments about bar charts:

[T]he purpose of a chart or graph is to make one point, vividly.

I think we’re in agreement on this point. Seth mentioned non-scientists, so I guess another underlying theme is “don’t make them think about this information”. I think we can agree that sometimes that’s also our intention. [Read more…] about Bar graphs vs. Pie charts

Seth Godin gave his suggestions for using charts in presentations in The three laws of great graphs. He said that

There are 314 principles for good graphs and charts [in presentations]. But these three laws will take you far.

1. One Story
2. No Bar Charts
3. Motion

These are good laws, though I would like to modify law number 2 to read “Choose Chart Types Intelligently”. The following are my restatements of Seth’s points, with additional commentary about my version of his law number 2.

1. One Story
The reason to use a chart in a presentation is to make a point, to tell a story. Make sure each chart tells the story you want people to hear. No distractions, no side stories. Keep it simple, and keep to the point.

2. Choose Chart Types Intelligently
Seth doesn’t like bar charts. That’s cool. I like bar charts, but only where they are used appropriately. Seth points out how bad bar charts are for time series data, and it’s true, line or area (or XY!) charts are a better means for showing trends over time. Seth also shows an ugly 3D bar chart, and it’s also true that 3D effects reduce the effectiveness of your graphics.

However, bar charts are well suited for displaying categorical data. The important point is to keep it simple, and keep to the point.

3. Motion
Use motion to help tell a story. This doesn’t mean use a lot of animation, zoom the chart in from Neptune, and drop data points from the sky by parachute. It means a technique as simple as showing two charts, “before” and “after”, on successive slides or even side by side, where the charts are aligned and use the same axis scales. In fact, if the charts are adjacent, motion isn’t necessary, and it is easier for the audience to make comparisons.