Tuesday, November 20, 2007

Visualizations as Metaphors

There is a mini 'industry' of professionals who worry about data visualization. Which is great. Someone has to! I have a few of them in my Interesting Links on this blog - check them out if you have some time (Many Eyes, Swivel, Information Aesthetics, DSA Insights, Perceptual Edge).

Part of what they discuss and debate is efficient ways to convey insight from information - similar to some of the posts on this blog, but their concern is more with the physical display. What's the best way to arrange data in a graph? What is the best graphical representation? What types of annotations are acceptable, etc.

However, having read many of the thoughts and postings in this area, there is another way to look at visual representations of data that has less to do with efficiency of display, and more to do with impact - visualizations as metaphors.

I love metaphors. My previous boss was a metaphor giant - which can be a double edged sword when swung too liberally. But as a way to add impact to data, the visual-as-a-metaphor is invaluable.

Case in point. Here is a post on Juice Analytics regarding the evils of pie charts. The image is:

Now I love the guys at Juice, they are very sharp and smart. And their reasons as to why this is a bad chart are valid - too much visual for too little data and the 3d is kind of pointless.

They also quote some nasty comments made about the poor pie chart. One that caught my eye was from Eric G. Myers's Improving Customer Experience blog:

To my mind, the best use of a pie chart is when you have one value that is overwhelmingly larger than the rest and you don't want the audience to focus on the actual values, but just bamboozle them with the overwhelming size of the leading segment. Of course, this seems to come close to embracing the old adage, "There are lies, damn lies and statistics."

Eric, you hit the nail on the head! You just hit it with the wrong end of the hammer. This is EXACTLY the right way this type of visual should be used. You throw it up on the screen and scare the living daylights out of the audience with the large, overwhelming pie piece that dwarfs all other pieces! If it's competitive market share, then the imposing piece of pie is a looming metaphor for struggle and toil in the face of incalculable odds. If you arrange it just right, you can make your tiny sliver (of market share) even smaller and seemingly in danger (if it's all in 3d) of being eaten alive by your competition - the impending Cheesecake of doom!

Ok, so that's a little over the top, but you get the point. The image becomes a powerful call-to-arms to combat the invading competition. Or perhaps a reality check for the task ahead? In any case, it's more impactful for delivering your message than any table or set of numbers ever could be.

Just like great design is full of metaphors, great data visuals can be too. Especially if they exist to make a point or further an argument. Not all data displays are static reports delivered as cold, hard facts. Which means not all visualizations are flawed if they don't follow the rules for cold, hard, factual static reports. Something to keep in mind.

Edward Tufte calls this the greatest data visualization ever. I think I agree. But not because it crams more information into less space than anything else could. It's the fact that it LOOKS like a jagged, disorganized, unplanned and unforeseen tragedy.

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Chris said...

I agree that the chart can be used as art and there is an occasional need to propagandize to get a message across.

In defense of our post, the pie charts we're showing aren't being used in that context. They're just trying to communicate a number. And they don't do it well.

Paul Soldera said...

I completely agree Chris. And I have no problem with anything you guys said regarding pie charts.

I guess I was just making the point that context and meaning (if you are trying to make an argument) can dictate physical construction as much as 'good practice'.

'propagandize' is kind of strong - at least in as much as it has a slight negative connotation around 'mislead'. I'd never endorse misleading visual metaphors. But there can be a fine line.

Tony said...

Excellent use of bamboozle!

It really depends. A pie chart is what's expected by the majority of folks. It can probably do a pretty good job of distinguishing between two values that have a large deviation. In the juice example, why not just state that new visitors make up roughly 10 times the visitors compared to returning visitors.
I agree that a table on a slide probably wouldn't solicit the same response as a visual, whether it is pie, bar or other method.

Now if we are talking about a dashboard, then I can confidently state that pie charts have no good place.