Visualizing data with lines, blocks, and roller coasters
April 25, 2011 8 Comments
Randall Munroe's infographic on radiation dose levels (Click to enlarge)
I’m a huge fan of clever ways of visualizing data, especially when there’s something challenging about the data in question. For example, if it contains more than three important dimensions and therefore can’t be easily graphed with the typical representations (e.g., position on x-axis, position on y-axis, color of dot). Or if it contains a few huge outliers which distort the scale of the data.
This recent infographic in Scientific American by my friend (and co-blogger, at Rationally Speaking) Lena Groeger is a great example of the latter. The challenge in displaying relative levels of radioactivity is that there are a few outliers (e.g., Chernobyl) which are so many times higher than the rest of the data that when you try to graph them on the same scale, you end up with the outlier at one end and then all the rest of the data clumped together in an indeterminate mass at the other end.
Randall Munroe over at the webcomic XKCD came up with a pretty good, inventive solution that relies on our intuitive sense of area, rather than length. Each successive grid represents only one small block of the next grid, which is how he manages to cram the entire skewed scale into one page. It’s cool, but I don’t think it works that intuitively. We have to consciously keep in mind the reminder of how big each grid is relative to the next, and it’s easy to lose your grip on the relative scales involved.
However, one of the benefits of online infographics as opposed to print is that you don’t have to fit the whole image in view at once. Lena and her colleagues created a long, leisurely scale that has the space at one end to show the differences between various low levels of radiation dose, below 100,000 micro-Sieverts… and then it hits you with a sense of relative magnitude as you have to scroll down, down, down, until you get to Chernobyl at 6 million micro-Sieverts.
It reminded me of one of my all-time favorite data visualizations: over one hundred years of housing prices, transformed into a first-person perspective roller coaster ride. There are a number of wonderful things about this design choice. For one thing, it works on a visceral level: reaching unprecedented heights actually makes you feel giddy, and sudden steep declines are a little scary.
I also love the way it captures the most recent housing bubble — as you keep climbing higher, and higher, and higher, and higher, and higher, the repetitive climb starts to feel relaxing, and you even forget that you’re on a roller coaster. You forget, in other words, that you’re not going to keep going up forever. And that moment at the end, when the coaster pauses and you turn around to look down at how far away the ground is (this video stops right before the 2008 crash) — shiver. Just perfect.
That housing bubble rollercoaster is great. (I’m stealing it to repost elsewhere.) It would be even greater if it were updated for the past few years, though.
Personally, I liked the xkcd chart, but that’s probably because I’m a physicist and accustomed to thinking in orders of magnitude. Maybe it would work better set up like the Scale of the Universe Flash demonstration.
This is one of the better graph illustrations I’ve come across lately. Worldwide Health and Wealth changes over the last 200 years http://www.youtube.com/watch?v=jbkSRLYSojo
XKCD fit the observable universe in one picture by using a log scale.
http://xkcd.com/482/
Cool graphic, but do you think it works on an intuitive level? I don’t think my brain is very good at grasping differences on a log scale. Something the the Powers of Ten video gives me more of a sense of relative magnitude: http://www.youtube.com/watch?v=0fKBhvDjuy0
The SciAm depiction of radiation dose reminded me of the standard dB/log scale depictions of sound levels and the EM spectrum.
http://www.osha.gov/dts/osta/otm/noise/images/a_weighted_sound_levels.gif
http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edit.svg
Drawing the radiation on a linear scale seemed weird to me. They had to cut a huge chunk out of the scale to make the Chernobyl reactor fit in the picture.
With visceral visualizations, watch out for the perils of metaphorical thinking.
The roller coaster goes up slowly, but house prices went up as fast as they came down, and they didn’t drop all the way to the bottom.
http://bit.ly/eIjEjc
(Graph on page 2)
A steep drop followed by a quick rebound may be scary on a roller coaster, but a long slow descent is worse when it comes to prices.
Excellent point, Max — the visceral scariness of the coaster doesn’t track exactly with the actual danger of the phenomenon it’s representing.
If everbody is posting xkcd visualizations then I’ll have to post his best one:
http://xkcd.com/657/
I don’t really like the rollercoaster one much. It’s perhaps better if you have some background knowledge of the overall patterns already, but not being american and not knowing much about housing prices, the slopes don’t mean much to me. I would probably be able to learn alot more from a simple line graph.