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Making Pie-charts look Sexy – The CNN’s tax burden analysis chart

Posted on October 29th, 2008 in Analytics , Charts and Graphs - 10 comments

There is always a debate about how good or evil pie charts are. While visualization purists believe pie charts should be avoided at all costs, newbies find creating and using pies very easy and often over do it. I have blogged few techniques involving pie chart visualizations like in-cell pie charts, speedometer charts, donut clocks and the response from readers has been mixed.

A good example of Pie Chart Usage

My opinion with respect to pie charts is that, when used in moderation they are OK. I say this because of the overwhelming awareness of pie charts. You can go and show it a school kid with the same comfort level as you can to your CEO and both will interpret the message in the same way (that is provided your pie chart is interpretable). Also, pies with 2 or 3 slices tend to be easier to understand.

Yesterday, I saw this very good example of using pie-charts in moderation at CNN’s Where tax burden falls chart (see it on the right)

The chart shows, how tax payers and tax burden is broken up across each of the income ranges. It enables quick analysis of disparities between income, representation % and contribution % in simple, understandable pie chart form.

Also, see how they avoided the trap of making two big pie charts. despite having the choice putting 2 giant pies (one for tax payer % breakup by bracket, another for how much taxes each bracket paid) these folks avoided that trap and chose to stick to multiple pie charts. If you had combined them in to two pie charts, I am sure it would have been a disaster. (corrected to make it simple to understand :D)

What is your stance on pie charts?

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10 Responses to “Making Pie-charts look Sexy – The CNN’s tax burden analysis chart”

  1. Matt says:

    I agree that the table version of the pie charts is easier to see than 1 single pie chart. However, you have the actual numbers in the table. Do the pie charts really add anything? I found myself just looking at the numbers. I can’t see the difference between 18, 20, and 17% in the pie charts anyway. I don’t think any information is added by the pie charts.

  2. Robert says:

    This might be a duplicate comment (my first try didn’t work). If so, I am sorry.

    I wrote:

    Chandoo,

    call me a visualization purist, but again I would have used two bar charts for this.

    And I would not even call these ones pie charts. To me they look like Harvey Balls with a higher level of detail.

  3. Tony Rose says:

    A simple table would suffice for this data. The pie charts don’t add true value.

  4. Chris says:

    I liked these charts as well (though they are somewhat superfluous). My thought for improvement though would be to rotate each segment as you move down the list. That is, since we’re really seeing one pie chart in each column anyway (with each slice given its own pie) rotating the pieces to where they would fit would make that more visually obvious. Thoughts?

  5. Chandoo says:

    @Matt: you have a valid point… However most of the charts usually carry data labels (or axis grid lines) simply because we are too bad at interpreting angles or heights.
    @Tony: In fact this one is a table, aided by pie charts (not the other way around). I am sure CNN folks must have thought the same way you did.
    @Robert: I am sorry, for some weird reason your first comment was blocked by spam filter.

    Using two bar charts is another good option.

    @Chris: Good point, Even I have thought about the same. But probably arranging the orientation must be a difficult option both work-wise and interpretation-wise. Without changing orientation it may be easier to compare two values.

  6. derek says:

    I don’t disagree that pie chart segments are difficult to interpret, although I would have thought their defenders had a better opinion of them than that. I do disagree that the work would be difficult. It’s exactly the same method as one uses to make a waterfall chart, and a similar method to the one you used to make the speedometer gauge.

    In fact I would argue that it would be physically just as fast to make an orientated set of pies as it was to make a set where each slice had to start at zero, because then you had to make a different pie every time. With orientation, you could keep re-using the same pie, and just change the colors of the slices. But I’d still prefer a waterfall.

  7. DMurphy says:

    I like the overall impression the charts give and it is that “quick feel”, after all, what Pie Charts are supposed to give – the values then allow you to home in on the specifics.

    My only comment would be to CNN who missed the opportunity (depending on who you are going to vote for next week, I suppose) on a third set showing the burden of tax on each income group (to save you working it out, it’s the 540k income group who pay the greatest portion – 34.6%).

  8. Chandoo says:

    @Derek: that is a cool suggestion to arrange the orientation of pies. I never thought of that.

    @DMurphy: another good suggestion there. I doubt if the entire set of folks in the $540k avg income range ($500k to $1m) pay the same portion though (34.6%) as there are tons of clauses to save people from paying more…

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