A friend of mine pointed me to a story in today’s WSJ (no subscription needed) with a hard to understand graphic in it. I’ve pasted the graphic below.
The designer chose to use the entire background of the chart to represent the number of sudden cardiac deaths in a given year. They used squares of different sizes to represent the number of explained and unexplained deaths from cardiac arrest. In this case, I think the designer was trying to give the reader an easy way to compare the parts to the whole, but it doesn’t work. Also, there are over 100 words of annotation on this otherwise skimpy graphic, which makes me think they could have done away with the graphic and just used the words instead.
Here’s the WSJ graphic:
Here’s what I think the chart should look like:
What do you think? Is my graphic clearer than the WSJ’s? What would you do differently? I’d love to hear your comments.
This is a similar problem addressed in a blog post of mine about charting disproportionate values: http://www.datadrivenconsulting.com/2009/12/charting-data-with-one-disproportionally-large-value/
Ideally I would want to keep the scale the same as you slice the data, but you can’t use a consistent linear scale in this case as the 350,000 total is so much larger than the 800 or so people who show positive for these genetic markers. So the natural choice (?) is to switch to an area, allowing you to decrease the dimensions – hence bubble charts and their ilk. Now they of course have their issues as we know.
I tried a few things like having the 350,000 be the background for the whole image, but nothing was that satisfactory. I think your option is probably the best, if you’re going to chart it. Perhaps just text would work just as well.
If you’re going to use an area format like the original, I’d change the color of the light gray 350k to a dark color for contrast. I’d also use a square instead of a bar when slicing from 10,000 to 3000 – keep the shapes consistent.
I really like that post of yours Alex. Before I created my viz, I searched and searched for a post I remembered reading on how to produce a chart with one disproportionally large value. I couldn’t find it, but now I know where I saw it, it was your post! You put together some great examples on how to deal with this problem, an you got some great comments on the subject too.
After reading the comments on your post, I think Joe Mako’s suggestion of a dot plot is quite good, as is Funky Gawy’s suggestion to “fill up a 30×29 grid with these symbols for the human category, but fill a much smaller 5×6 grid for all the rest. This is so often done inappropriately but this might be the paradigmatic use.”
I’d like to see someone take a shot at Funky’s idea with this example.
John
Your Viz is much better than the WSJ, as it encodes a waterfall effect that is truly needed. Of Course, if the viz was interactive then the same effect could be captured by drilling into the areas you depicted with arrows. But to be consistent I would keep the color scheme consistent. i.e. the drill down portions of the bars should be the same color. In your Viz you drilled down on ’40 and under’ which was colored black, then you drilled down on ‘Unexplained death’ which was colored gray. Lastly, on the xAxis of the third Viz I would have labeled them ‘Genetically Explained’ and Genetically Unexplained’ vs Unexplained death and Explained Death.
All in all a great Viz !