Thursday, January 27, 2011

A Correction for Jon Peltier

The way the web works is funny. I have been reading Jon Peltier's blog for several years now, and learned a lot of what I can do in Excel, and about principles of design from his blog (and ones like it). I was shocked when he commented on my blog when I wrote about basic principles of data visualization for baseball. I was possibly more shocked when I read his comment and realized that he was very right and I'd made a charting faux-pas.

Here is the chart he takes issue with:

Jon doesn't like pie charts much. In the data visualization community, there's been a lot of back and forth over whether pie charts are useful. Since they are used everywhere, people are familiar with them, so I look on them a bit more favorably than Jon does, but that wasn't the essence of his complaint.

You should never use multiple pie charts if you're going to compare them. It's just no easy to compare the size of slices across multiple pie charts.

So instead, Jon recommends using bar charts, like this:

And I think I have to admit it looks a lot better, and is a lot easier to compare between the various players this way. I still think pie charts are okay if you keep them simple, but I didn't follow my own advice and keep them simple enough. This is probably more the proper simplicity:


  1. The bar charts make it much easier to compare stats. They are also more flexible: you can show percentages as you did, or you could compare the raw numbers instead, which would be impossible in multiple pies.

    In the right setting (the small blue wedge in your last chart, he he), pie charts are a reasonable choice. I guess I'm pretty vocal about them because they are used in the wrong setting so much of the time.

    P.S. You got out of Beantown just in time. I had to shovel another foot of snow today.

  2. What are you talking about Jon? I could just make the pies variable sizes to show the raw numbers!

    (just kidding)