2-D or not 2-D? (That is the question)
January 16, 2006
We can learn how to be better presenters by observing the masters. I often say, for example, that we can improve our presentations by emulating certain aspects of Steve Jobs' presentation style. Today, though, I'd like to talk about one aspect of Steve's presentation Tuesday that we can learn from by not emulating. And that is the use of 3-D charts to represent 2-D data.
At Tuesday's Macworld keynote, Steve announced — almost parenthetically — that many new features have been added to the newest version of Apple's presentation software, Keynote. Long before the announcement, however, it was apparent that something was different about the slideware Steve was using. The first indication came when he showed a 3-D pie chart (complete with a wood-like texture) representing the market share for iTunes. Although the iTunes market share figure was the point, it was the pie chart that people seemed to notice more. Many of the new Keynote features are quite useful, but the 3-D tool, which was not available in previous versions, is one I could do very well without.
One idea I keep coming back to here is the notion of simplicity. But taking 2-D data and creating a 3-D chart does not simplify. In The Zen of Creativity, author John Daido Loori, commenting on simplicity, says that the Zen aesthetic "...reflects a simplicity that allows our attention to be drawn to that which is essential, stripping away the extra." What is essential and what is extra is up to you to decide, but stripping away the extra ink that 3-D charts introduce seems like a good place to start. 3-D representation of 2-D data increases what Tufte calls the "ratio of ink-to-data."
One reason why Keynote charts looked so good in the past, even if people were not conscious of the reason, was because graphs and charts were always 2-D. Users had no choice. Now Keynote users will have a choice. And while it's nice to have a choice perhaps, 2-D charts and graphs will almost always be a better solution. 3-D charts appear less accurate and can be difficult to comprehend. The angular relationship of the 3-D charts often make it hard to see where data points sit on an axis.
Is it decoration or is it design?
Slapping on tired textures such as marble and wood is not only decorative, it is ugly. I have received several emails and comments since Tuesday about the 3-D charts in the keynote. "It's so '90s PowerPoint," said one woman. "It's so non-Apple looking," said another. "Yuck!!!" wrote yet another reader.
Gary Klass, from Illinois State University, has an older article called "How to Construct Bad Charts and Graphs" which is a summary of Tufte's ideas on this issue. Pay particular attention to the section on "Data Distraction" which compares a 3-D column bar with a 2-D bar. Here's an excerpt from the article:
"The primary source of extraneous lines in charting graphics today are the 3-D options offered by conventional spreadsheet graphics. These 3-D options serve no useful purpose; they add only ink to the chart, and more often than not make it more difficult to estimate the values represented. Even worse are the spreadsheet options that allow one to rotate the perspective."
— Gary Klass
Data is not to be feared
From the Keynote section of Apple's website: "Now neither you nor your audience need fear the appearance of a chart or two. Designing eye-catching (3-D) charts in Keynote 3 is as easy as creating them." What are they saying? That our heretofore 2-D visual representations of our data were necessarily intimidating? That our audiences are stupid? Apple seems to be saying that our audiences now "need not fear the appearance of a chart or two" because we can now make things easier to understand visually in 3-D. But 3-D charts do not simplify, they complicate, distort, and can give false impressions.
Blame it on marketing?
Software companies have to keep improving their products and feel the need to add "new and improved" features. Otherwise, why buy the latest version, right? Perhaps the inclusion of 3-D charting capability comes down to marketing and perception. For example, now no one can say "Keynote's no good — it can't even do 3-D charts!" Now it can.
Except for the three slides with 3-D charts in Steve's presentation, his visuals were good overall. Perhaps Steve used 3-D charts in the course of his presentation to not-so-subtly highlight Keynote's new capabilities. No matter the reason, we can take the occasion here to learn from this minor design miscue.
Above: Is this a pie chart or a picture of a coffee table gone bad? A skewed perspective and as aesthetically pleasing as brown shoes with a black tuxedo.
Above: A couple of simpler options which took about 30 seconds to make in Keynote. These are not necessarily perfect either (e.g., do the shadows add to the perceived area of the largest slice? Does the texture help or hurt? Contrast? etc.).
Above: Steve discusses how they've been trying to shoehorn a G5 into the PowerBook, but have been unable to do so due to the power consumption of the chip. It was not just about performance but "performance per watt," he said. The G4 chip has 0.27 "performance per watt." The Intel Core Duo has a much better "performance per watt." The third bar really "towers" over the other two in part due to the higher position of the baseline on the right. But the first bar can also appear larger than the data would support since it appears closer and has a visible top.
Above: Two possible treatments in 2-D (generated in moments in Keynote 2). Again, these are not without issues either (personally, I am not a fan of textures in bar charts). One option was to group the two bars on the left as they are of the same family (PPC). The point of the chart was to show the difference between the PPC chips and the new Intel chip in terms of performance per watt.
Above: This chart was on screen for about 12 seconds (built bar by bar). This chart is aesthetically challenged (though that may be a matter of taste) and has the usual problems of distortion and an increased "ink-to-data ratio" as a result of the 3-D perspective.
We also must be careful not to exaggerate differences by shifting the baseline to a higher number. In the chart above, Steve is showing Mac sales over the past year. To be sure, it was a very good year for Apple and Mac sales were up over the previous year (and iPod sales were up even more). But the chart exaggerates the growth which took place from quarter to quarter. It visually seems very dramatic because 1,000,000 is used for the baseline. As a result, it seems that 1.25 million units in Q4 is more than double the 1.07 million units sold in Q1.
Above: On the left is a 2-D version of the same data on Mac sales by quarter with a baseline of 1,000,000. On the right you can see how less dramatic the increase appears quarter to quarter when the data are displayed in a more straight forward manner (baseline is 0).
If it walks like a duck...
Don't let the visual display of your data turn into a "Big Duck." The term "duck" was inspired by the Big Duck and was used originally "to describe a building in which the architecture is subordinate to the overall symbolic form." In The Visual Display of Quantitative Information, Edward Tufte uses the term to refer to graphical decoration and visual noise:
"When a graphic is taken over by decorative forms of computer debris, when the data measures and structures become Design Elements, when the overall design purveys Graphical Style rather than quantitative information, then the graphic may be called a duck in honor of the duck-form store..."
— Edward Tufte
3-D charts can be stylistic, but mostly they are misleading. If you are considering using 3-D charts, always ask yourself "does this treatment help or does it just result in a 'big duck?'" In Visual Explanations, Tufte has many good examples on when and how to implement 3-D graphics. 3-D representations of cloud formations or spaces, etc. can be very useful.