Comments on: Pie charts: a neverending discussion http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/ Business Charts, Done Right Sat, 06 Mar 2010 23:42:23 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Hadley Wickham http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-156 Hadley Wickham Fri, 26 Oct 2007 15:44:23 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-156 Oh, I see that Spece cite's a few. It just doesn't ring true to me - from experiments that I've seen pie charts are much inferior to pies - I find it very hard to accurately judge the angles. Maybe the difference is that bar charts normally have scales and pies don't, but the experiments use scales for neither. Oh, I see that Spece cite’s a few. It just doesn’t ring true to me – from experiments that I’ve seen pie charts are much inferior to pies – I find it very hard to accurately judge the angles. Maybe the difference is that bar charts normally have scales and pies don’t, but the experiments use scales for neither.

]]> By: Hadley Wickham http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-155 Hadley Wickham Fri, 26 Oct 2007 14:55:35 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-155 Oh come on, there may be many reasons to prefer a pie chart over a bar chart or dot plot, but perceptual accuracy isn't one of them. Can you find one peer-reviewed article that states otherwise? Oh come on, there may be many reasons to prefer a pie chart over a bar chart or dot plot, but perceptual accuracy isn’t one of them. Can you find one peer-reviewed article that states otherwise?

]]> By: Chris P http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-154 Chris P Fri, 26 Oct 2007 14:52:25 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-154 The wikipedia entry on pie charts points to Cleveland, and does try to take the tone that pie charts are to be avoided. My reading of treemaps is that they are just a little less cryptic than pie charts. I see pie charts as a necessary evil--like using a passive sentence in writing just to have some variety. As long as I am not making comparisons and don't have more than a few slices, and the labels fit on the graph and not on a legend, and I have a bunch of bar charts in the work, then I will add a pie chart. The wikipedia entry on pie charts points to Cleveland, and does try to take the tone that pie charts are to be avoided. My reading of treemaps is that they are just a little less cryptic than pie charts. I see pie charts as a necessary evil–like using a passive sentence in writing just to have some variety. As long as I am not making comparisons and don’t have more than a few slices, and the labels fit on the graph and not on a legend, and I have a bunch of bar charts in the work, then I will add a pie chart.

]]> By: admin http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-153 admin Thu, 25 Oct 2007 20:15:08 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-153 <p>Hadley: Spence in the link above discusses Cleveland's hierarchy, Simkin and Hastie findings and his own work. unfortunately there is no accepted scientific answer. There is some fragmented knowledge but the puzzle is far from finished.</p> Hadley: Spence in the link above discusses Cleveland’s hierarchy, Simkin and Hastie findings and his own work. unfortunately there is no accepted scientific answer. There is some fragmented knowledge but the puzzle is far from finished.

]]> By: Tony http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-152 Tony Thu, 25 Oct 2007 20:03:07 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-152 Makes me want to slap down some money and spin it! Makes me want to slap down some money and spin it!

]]> By: admin http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-151 admin Thu, 25 Oct 2007 19:07:00 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-151 Jeff: thanks for the link. Like mine, is a balance view of the problem. By default I wouldn't use multiple pies, specially as a map overlay jerjer: I updated the post to include a link to a post in Seth Godin's blog that deals with too much data (also in pie charts). I like a pie chart with two slices when it is used as a visual clue to show a subset. At least one of the slices must be linked to a "proper" chart (in this case, the pie chart is more a "design device" than a real chart... Jon, Tony: Do you know that there is a (very basic) add-in from Microsoft Research Community to create treemaps in Excel? It's called (surprise, surprise!). You can get very interesting results with a treemap if the dataset is right (high variability, for example). Tony, this is the default pie chart in Xcelsius... Jeff: thanks for the link. Like mine, is a balance view of the problem. By default I wouldn’t use multiple pies, specially as a map overlay

jerjer: I updated the post to include a link to a post in Seth Godin’s blog that deals with too much data (also in pie charts). I like a pie chart with two slices when it is used as a visual clue to show a subset. At least one of the slices must be linked to a “proper” chart (in this case, the pie chart is more a “design device” than a real chart…

Jon, Tony: Do you know that there is a (very basic) add-in from Microsoft Research Community to create treemaps in Excel? It’s called (surprise, surprise!). You can get very interesting results with a treemap if the dataset is right (high variability, for example).

Tony, this is the default pie chart in Xcelsius…

]]> By: Hadley Wickham http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-150 Hadley Wickham Thu, 25 Oct 2007 15:14:33 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-150 Why not use some science to answer this question? No one has mentioned Cleveland's hierarchy yet, which reminds us that the perception of distance on a common scale is (much) more accurate than perception of angle or area (so applies equally well to treemaps too). If we want a graphic than can be perceived accurately, we should favour a bar chart (or even better, a dot chart) over a pie chart. While a bar chart loses the clear part-to-whole relationship of a pie chart, this can be included in a caption or with other graphical means. If you're not aware of Cleveland's pioneering work in this area, I would highly recommend that you look into it: W. S. Cleveland and M. E. McGill. Graphical perception: Theory, experimentation and application to the development of graphical methods. Journal of the American Statistical Association, 79(387):531–554, 1984. Why not use some science to answer this question? No one has mentioned Cleveland’s hierarchy yet, which reminds us that the perception of distance on a common scale is (much) more accurate than perception of angle or area (so applies equally well to treemaps too). If we want a graphic than can be perceived accurately, we should favour a bar chart (or even better, a dot chart) over a pie chart. While a bar chart loses the clear part-to-whole relationship of a pie chart, this can be included in a caption or with other graphical means.

If you’re not aware of Cleveland’s pioneering work in this area, I would highly recommend that you look into it: W. S. Cleveland and M. E. McGill. Graphical perception: Theory, experimentation and application to the development of graphical methods. Journal of the American Statistical Association, 79(387):531–554, 1984.

]]> By: Tony http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-149 Tony Thu, 25 Oct 2007 14:30:43 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-149 Jon - I am a little intrigued by the treemaps. However, I see some of the same pie chart problems with treemaps. Although, maybe it's better than a pie, I still have difficulty judging the difference in scale between a verticle rectangle/square and one that's horizontal. I end up tilting my head sideways to see if I can compare them, which I find inefficient and prone to neck muscle strains. I also agree with Derek that sometimes a simple table is sufficient! Jon -

I am a little intrigued by the treemaps. However, I see some of the same pie chart problems with treemaps. Although, maybe it’s better than a pie, I still have difficulty judging the difference in scale between a verticle rectangle/square and one that’s horizontal. I end up tilting my head sideways to see if I can compare them, which I find inefficient and prone to neck muscle strains. I also agree with Derek that sometimes a simple table is sufficient!

]]> By: derek http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-148 derek Thu, 25 Oct 2007 13:53:55 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-148 I too am fond of conceding that a pie chart with only two slices is relatively harmless. But there's a problem with conceding that they're relatively useful, because the space available to them to be relatively useful does not extend all the way down to zero: at some point the usefulness of a simple pie graph drops below that of an equally simple table, or even a simple chunk of text. Who is unable to interpret the phrase "25%", or "1/4", or "3 to 1"? And if no-one who could interpret a pie chart with ease is unable to interpret such text with equal ease, what is a pie chart but pretty wallpaper? I too am fond of conceding that a pie chart with only two slices is relatively harmless. But there’s a problem with conceding that they’re relatively useful, because the space available to them to be relatively useful does not extend all the way down to zero: at some point the usefulness of a simple pie graph drops below that of an equally simple table, or even a simple chunk of text.

Who is unable to interpret the phrase “25%”, or “1/4″, or “3 to 1″? And if no-one who could interpret a pie chart with ease is unable to interpret such text with equal ease, what is a pie chart but pretty wallpaper?

]]> By: Tony http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/comment-page-1/#comment-147 Tony Thu, 25 Oct 2007 12:35:48 +0000 http://www.excelcharts.com/blog/pie-charts-a-neverending-discussion/#comment-147 Jorge, this is a great visual to reinforce the message. Can anyone tell me by looking at the pie chart above, how the yellow and grey pie slices compare? Which is bigger? You wouldn't have that problem using a y-axis bar chart. The things I can tell by looking at the pie: green is the largest and the parts add up to the whole. Great work Mr. Pie [hint of sarcasm]! Jorge, this is a great visual to reinforce the message. Can anyone tell me by looking at the pie chart above, how the yellow and grey pie slices compare? Which is bigger? You wouldn’t have that problem using a y-axis bar chart. The things I can tell by looking at the pie: green is the largest and the parts add up to the whole. Great work Mr. Pie [hint of sarcasm]!

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