The Grand Principles of Information Display

Notes from Edward Tufte’s lecture (thanks to David Stack)

The First Grand Principle: Enforce Wise Visual Comparisons., i.e., force answers to the question “Compared with What?”

The Second Grand Principle: Show Causality. We are looking at information to understand mechanisms. Policy reasoning is about examining causality. Napoleon was defeated by the winter, not the opposing army, as shown by the temperature scale o n the bottom of Minard’s graph,

The Third Grand Principle: The World We Seek to Understand is Multivariate, as Our Displays Should Be. The Minard graph has six dimensions: size of the army, the two dimensional route of the march, the direction of the march, the temperatures and the dates.

The Fourth Grand Principle: Completely Integrate Words, Numbers and Images. Don’t let the accidents of the modes of production break up the text, images and data. Just because the artists, technical writers and database people work in differen t buildings doesn’t mean reports should be disjoint with text, graphs and images in different boxes or on different pages.

The Fifth (most important) Grand Principle: Most of What Happens in Design Depends upon the Quality, Relevance and Integrity of the Content. Minard’s graphic was made as an anti-war poster. To improve a presentation, get better content. If your numbers are boring you have the wrong numbers. Design won’t help, it is too late.

Page 18 of Envisioning Information shows a book by Galileo published in 1613 which reported the discovery of sunspots and the rings of Saturn for the first time. He wrote in Italian, not Latin, because he wanted to reach a wider audience than the scientific elite. His tone of writing is wide eyed, straight-forward, undiplomatic, sardonic and sounds a lot like the modern voice of Richard Feynman. The report of the discovery of sunspots has a simple drawing of the sun on each page to show daily obser vations. From these observations he learned that the sun was rotating as the spots moved across the page and changed apparent shape at the edges due to foreshortening. It is easy to make comparisons between the left hand and right hand pages because the y are within the eye span.

The Sixth Grand Principle: Information for Comparison Should be Put Side by Side., i.e., within the eye span, not stacked in time on subsequent pages, which is known as ‘one damn thing after another’, and also known as the computer interface. The computer interface is a low-resolution display device compared to paper, so we have a relentless sequentiality. The most common user question after a sequence of computer operations is “Where am I?” The lesson: get the biggest monitor of the highest resolution that you possibly can.

One of Tufte’s students scanned Galileo’s images and animated them so the sun of 1612 could be seen to rotate. At a couple points in the annimation the images skip forward because there was missing data due to clouds, or Galileo taking a day off.

A Jesuit rival of Galileo republished the sunspot data (see p17 of Envisioning Information). He used the single most effective tool of information design, the small multiple, which puts all 38 images within the eye span.

The Seventh Grand Principle: Use Small Multiples. They are high resolution and easy on the viewer, because once the viewer figures out one frame, they can figure out all the rest based upon what they have learned. It escapes flatland by introd ucing time as a variable. They have an inherent credibility with the viewer because they show a lot of data, i.e., “I know what I’m talking about and I’m showing all my data to you.” Keep the underlying design of small multiples simple and clear.

A good example of small multiples is on pp 30-31 of Envisioning Information which shows the NY Times report of the acquittal of John Gotti based upon a chart introduced by the defense. It was done with Lotus 1.2.3, but Lotus has never used it in their advertisements.

On pp 120-121 of Envisioning Information it shows how Galileo reported the first telescopic observations of the rings of Saturn. Modern texts would report this discovery by saying, “See fig 17b”, or a modern designer would take the image, put it in Ph otoshop and wrap it around the book jacket.” Galileo says, “It looks like this”, and there is the illustration right in the text. We’ll be able to do this real soon now with digital publishing. Saturn functions as a drawing, a word, a noun.

The Eighth Grand Principle: Don’t Dequantify. Numbers have meaning. Use numbers or a graph that represents them. Don’t reduce quantities to on or off, yes or no, here or not.

These Grand Principles are universal. Everything in this seminar is directly relevant to the first map scratched in stone 6,000 years ago and, heaven forbid, web pages. Sometimes the best that information design can do is not screw up good content.

The meta-principle over all of these Grand Principles tries to answer the question about how we derive principles of information display. The meta-principle is: Thinking and designing are as one. If the cognitive task is to make comparisons, t hen our display should do the same. The principles of information design are the principles of reasoning about evidence. It is visual thinking. Good design is a lot like clear thinking, made visible.

The converse is also true. Bad design is stupidity made visible. If a chart has three phony dimensions to compare four numbers it shows the person doesn’t know what they are talking about. It doesn’t just show that they used Excel.

Start by asking, what is the intellectual task that this display is supposed to help with?

Edward Tufte on NPR


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