“No Pie Charts… Not Ever!” (says I)

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I am a big fan of letting users drive the features of a product.  In fact, we’re about to release a ranking survey based on the feature suggestions in the thousands of emails we’ve received over the past few months.

But one often-requested feature that will likely not be included in RescueTime is pie charts.

The very early mockups of RescueTime did have pie charts and I kinda liked them.  They broke up the bar-chart monotony and just seemed more fun.  As I continued to show and refine the mockups, it wasn’t long before crafty students of data visualization told me that pie charts were evil.  It didn’t take much listening and much research to agree with them.  Here are a few points for the consideration of pie-loving RescueTimers:

  •  Human beings are a lot better at eyeballing length than angle.  If you don’t believe, check out the illustration in the sidebar of the Pie Chart Entry in Wikipedia.
  • In Show Me the Numbers by Stephen Few the author says “I don’t use pie charts, and I strongly recommend that you abandon them as well.” Few says that pie charts communicate poorly.  Robbins agrees.  So does Tufte.
  • Pie Charts (with small slices) require a legend which necessarily has visual separation from the data.
  • Rotating a pie chart changes perception a bit, especially when the slices are of similar size.
  • Pie Charts convey magnitude poorly.  It’s difficult to eyeball the difference between a 22% slice and a 26% slice.
  • When the rubber meets the road and I test pie charts with RescueTime data with Pie charts, it just conveys less meaning (with 10 slices).

All that being said, I think that we could convey the “part-to-whole” information in your usage data a lot better than we are.

So, pie-people– I’m going to do my best to comply with the spirit of your request (“we want better part-to-whole visualization!”) rather than the letter of your request (“we want pie!”).  Stay tuned for it!


8 Comments on ““No Pie Charts… Not Ever!” (says I)”

  1. […] you in the face when you’re thinking about wasting time by reading your blogs. Also, as mentioned yesterday in Tony’s post about pies (mmmm), we’ve put up our new feature suggestions voting survey. There are a lot of things […]

  2. Jorge Camoes says:

    Poor pie charts… They are not so bad, people just don’t know how to use them, and when.

    I think this is a more balanced approach:
    Pie Charts: a Never ending discussion

  3. See-ming Lee says:

    I just downloaded your software and I look forward to testing it out. My comment below is based on your screenshots as I don’t have enough data yet.

    While I applaud your not using pie charts, it appears that you are using 3d bar charts. As an information designer, I’d prefer that you use 2d bar charts instead, as the z-index greatly diminishes the value of bar charts, for it makes it difficult to compare the height of bars.

    /SML

  4. Tony Wright says:

    Aha– very true. Our release this Wednesday will also abolish 3d charts (not to mention quite a few other enhancements!)

  5. Laurel Fan says:

    Another Edward Tufte fan?

    On the subject of charts, I think a timeline kind of view might be useful to see how the day goes. Since rescuetime is really the inverse cross product of google analytics and google calendar (you can quote me on that when you’re pitching the google buyout), maybe there are inspirations there.

  6. […] toolmantim: “No Pie Charts… Not Ever!” (says I) […]

  7. PollyQ says:

    OK, Pie Charts are evil, but I really do want to know what percentage of time I’m spending in various areas, not just absolute numbers. How about:

    * Stacked bar charts
    * % info as hover tips over bar chart
    * Separate bar chart that shows %
    * Multi-series bar chart, one for absolute, one for %