A square pie

I have always hated pie charts. I hated them even before L.E.K. trained me to use a stacked bar chart instead. This was a step forward, but wasn't ever quite right. Thanks to the guys at Juice Analytics, I've now (perhaps temporarily) fallen in love with the square pie chart.

For example, I was taking a look at the population of Iowa today. There were several layers to the problem. How many people are there? How many are of voting age? How many are registered to vote? How many of them are Republican, Democrat or Independent? Are they active or Inactive? Who can vote in the Presidential Caucus? A lot of questions. I tried to come up with a graphic that would answer all of these questions. A pie just wouldn't do, so here's what I ended up with:
You can already make out the red (Republicans), the Blue (Democrats) and the Purple (Independents). They look about the same and the labels on the detailed version will tell you the exact numbers. Then at the top you can see the Under 18 (dark grey) and the unregistered (light grey). As it turns out, only registered Democrats can attend the Iowa Caucus, and so there is bold line drawn around them to signify this.

I took this one step further when looking at other early presidential primary states:

At a glance you can see the relative size of the states' populations. Some are tiny compared to others. Some are Democrat-heavy. Some have no party registration at all (registered voters are all purple).

The small purple bar charts under each state show the number of registered voters per person who is eligible to vote in the Presidential Primary. The size of this bar gives you an idea of how many voters you must talk to in an untargeted campaign to fins a primary voter.

I deliberately blurred the data in the jpg on this site but I created it in PowerPoint, where the full detail is visible. While it works on a projector, the resolution of a regular monitor doesn't enable this kind of diagram to work. You just can't see the detail. Technology gets in the way! A pdf is helpful, because you can easily zoom in, but who wants to scroll around a pdf? The beauty of this much information on a page is that you can see it all, see patterns from afar and then look at sections for more detail without losing the overall picture. Until technology catches up and monitors get higher resolution, the only real answer for a diagram like this is to go old skool: print it out. It works like a treat!

Here's the Excel template I built for generating square pie charts. (Based on and inspired by the solutions to the excellent Juice Analytics challenge.)