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The Value of Illustrating Numbers

Showing data isn't always about trying to convey an insight, or giving people the means to understand the intricacies of data. It can also be a tool to communicate a fact, an amount, or an issue beyond just the sheer numbers. Data illustration is poorly understood, but it can be very powerful.

About a year ago, I had a Twitter conversation with Stefanie Posavec about the difference between data visualization and data illustration. We ended up with a sort of definition.

The source of this discussion was a video that was making the rounds at the time, and which I didn't find quite as impressive as a lot of other people. It shows flights in Europe over 24 hours.

I've since changed my mind about it, but two things bothered me: it was considered a visualization, even though I found that you could glean very little insight from it; and it did a poor job of showing how busy some of Europe's busiest airports were. That latter part is because it shows the actual flight paths, which all merge on final approach to landing, so the planes all blend together.

Why Illustrate?

All data is not created equal. There is basically no data you can't turn into a bar chart and get some sort of insight from. But some data just requires a bit more care and thought – not because of its structure, but because of what it represents.

When it comes to data about people, perhaps the approach needs to be a bit more thoughtful and respectful. Looking at data about homeless people, do we really need yet another goddamn bar chart? Is there not a more appropriate way to look at this data? Or think of the design process and thought that went into the 9/11 Memorial. This isn't the phone book, these are all individuals who died in horrendous ways.

Other examples include Periscopic's U.S. Gun Deaths, Pitch Interactive's Out of Sight, Out of Mind (about drone strikes), and the Huffington Post's Mapping the Dead (gun deaths for about three months after the Sandy Hook shooting in late 2012). They do not attempt to put numbers into perspective, because the perspective is not what matters. The goal is punch you in the gut, to make you feel something.


Numbers always invite comparison. But there is a point at which comparison becomes distraction and an excuse to minimize the number. Were there more traffic deaths than gun deaths in 2013? Probably. What other numbers can you find that are higher? But that's missing the point: to show the sheer number, no matter how it compares. It's the absolute number that counts. Everyone of those deaths is one too many.

What the gun deaths and drone strikes pieces (and, to an extent, the flights in Europe video) do so well is give you a sense of a number. This is the number, period. Don't try to compare, just appreciate that number. Get a sense of its magnitude. Feel it.

Illustration vs. Visualization

Among the many things we don't yet understand is the relationship and value of illustration compared to visualization. Illustrating a number is a noble endeavor, and one that needs to be done with thought and care. It's not an easy decision to make, and it's often hard to tell what a particular piece was built to achieve (and whether its creator had a clear enough idea).

The examples above give a bit of a sense of where I think things are headed. And I hope that we can be a bit clearer in distinguishing illustrations and visualization. Because both are important when trying to get a point across.

Posted by Robert Kosara on March 8, 2015.