Do you prefer the full report:
Or the executive summary?
For Tufte’s fans, Minard’s map plays a central role in Tufte’s iconography, and the way he praises it (“best statistical graphic ever”) is quoted endlessly (974 results in Google as of today, to be precise). Tufte discussed The Map in his first book (The Visual Display of Quantitative Information) and in Beautiful Evidence he uses it to illustrate six Fundamental Principles of Analytical Design:
- Show comparisons, contrasts, differences
- Casuality, Mechanism, Structure, Explanation
- Multivariate Analysis
- Integration of Evidence
- Content Counts Most of All
But, of course, they violate Seth Godin’s Principle of Make a Point in Two Seconds for Lazy People (here, about minute 2:40):
…this is one of the worse graphs ever made. He [Tufte]’s very happy because it shows five different pieces of information on three axis and if you study it for fifteen minutes it really is worth a thousand words. I don’t think that’s what graphs are for. I think they try to make a point in two seconds for people who are too lazy to read the forty words underneath. And to make me spend fifteen minutes studying it doesn’t make sense.(…) The kind of person he wants to reach they want to read a complicate, difficult to understand graph and get the satisfaction of figuring it out, because then they get it…
In this post he uses pie charts to further illustrate his principle:
Pie charts are a great example of how people go wrong. [First pie chart, eight slices] It’s accurate. It shows more than a half a dozen places that traffic come from. It’s also useless. It’s ungrokable. It doesn’t have a point. [Second pie chart, three slices, one of them exploded] Here’s the same data, grouped to make a point. “We get our traffic from three sources, one dominates the other two, but only one of them is under our control in terms of our ability to scale it directly. So let’s talk about how we grow that slice.”
Godin is not alone. Minard’s map also violates Kosslyn‘s Principle of Capacity Limitations and Principle of Compatibility:
The hazards of not respecting the limitations of human mental processes are nicely illustrated – ironically – by one of Tufte’s favorite graphics. (…) This display has never captivated me for the simple reason that given human processing limitations – I needed several minutes to figure it out. (…) I can’t agree that this is an effective way to communicate; the display doesn’t present the facts so that they’re clear or easily absorbed. If you are in the mood, you may enjoy taking the time to study the display for the fun of solving a puzzle, pondering intricate details, or appreciating the graphic devices employed. But if you want the facts and want them in a clear, easily understood way, this display is not the solution.
So, in order to design a better graph, Kosslyn proposes a new design that could take advantage of the Principle of Salience, Principle of Relevance, Principle of Perceptual Organization and Principle of Discriminability e makes a better use of the Principle of Compatibility. The end result doesn’t seem much better than some revisions of Minard in Michael Friendly’s Gallery.
(By the way, I’m also posting a series on design principles for better charts…)
I find all this slightly absurd.
The divide here is, of course, the level of detail you need or are prepared to accept. A good/bad chart is not defined by the time it takes to read it, it is defined by the insights you get from it and how efficiently it tells the story. Minard’s map is much better at this than the typical dashboard or presentation slide we are used to, a War and Peace in a single image against a boy-meets-girl-boy-loses-girl-boy-gets-girl plot in fifty slides.
Tufte says “to clarify, add detail”, but detail is a dangerous thing. It is the detail you choose that defines how you interpret reality, and it exposes your biases. Minard adds detail to explicitly link deaths to cold temperatures during retreat, but around 75% of men died on the way to Moscow and he doesn’t tell us why. You can seriously undermine your analysis by adding detail to the wrong places.
No details for Godin, please. He contradicts himself, but I suspect he couldn’t care less. He wants less data and a chart that makes a point in two seconds. But then he needs “to talk about how we grow that slice” and that means more data. Wouldn’t it be nice to have in the same chart something that helps him? Of course, that would require more than two seconds to read the entire chart…
At the end of the day, what really matters is how you manage your data. If your skills are poor, your charts will always reflect that, even if you are a Tufte fan and no matter how much detail you add…
So, do you believe that this is “the best statistical chart ever” or that’s something that we shouldn’t take too seriously?