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>use a pie chart or a donut. We know it's very controversial (data visualization mullahs tend to yell after anyone using a pie chart) but it's actually pretty u
by rm999 13y ago
>use a pie chart or a donut. We know it's very controversial (data visualization mullahs tend to yell after anyone using a pie chart) but it's actually pretty usefull in a business environment.
Translation: it's for people who (you think) want pretty plots instead of an actual understanding of the data. The article's repudiation of "mullah" (?!) opinion is a little anti-intellectual IMO - these people tend to have a lot of experience and therefore understand common pitfalls better than a lay person's intuition.
Pie charts do not work as intended in general, but may work in specific cases like the one the article shows. Pie charts have low perceived precision because people are bad at estimating radial distances. If in the article's example potatoes were 60 and rice 58, the pie chart would not convey that rice is lower than potatoes - they would look the same. A bar chart or stacked chart does not lose this information because humans perceive location with very high precision. There are several other pie chart failure scenarios, like too many categories, or very imbalanced categories, or very balanced categories. Overall, it's a very non-robust visualization method. It may look good in your presentation now, but when you get updated numbers you may find it becomes a mess.
- cyrillevincey 13y agoMaybe pie charts are not robust, but as I'm saying in the post, it's actually the best - if not the only - method to represent the contribution of the Top N contributors to a global measure. And only this. It's not meant to let the reader compare the relative measures of different items. If you wish to do so, I fully agree with your comment: use a bar chart instead.
- rm999 13y ago>it's actually the best - if not the only - method to represent the contribution of the Top N contributors to a global measure Yet it's still not great at that. Stacked bar chart (basically an unrolled donut chart) is better - again, because people perceive linear distances with much higher precision than radial: http://i1.wp.com/flowingdata.com/wp-content/uploads/2008/08/stacked-bar.png http://i1.wp.com/flowingdata.com/wp-content/uploads/2008/08/...
- scrollbar 13y agoI default to using treemaps for viewing composition of a whole http://en.wikipedia.org/wiki/Treemapping http://en.wikipedia.org/wiki/Treemapping
- cyrillevincey 13y agoTreemaps are very powerful during the data crunching phase, but they are not ok for a final deliverable, as they ask way too much to the reader's brain to get understood.
- scrollbar 13y agoMakes sense. I'm curious though, do you mean that even with the same number of categories for each it's too difficult? ie. instead of using hierarchical groupings and all categories no matter how small, use only the top ~10 and bucket the rest into "Other" similarly to a pie chart or bar.
- mbq 13y agoThe same goes for stacked plots -- they seem OK but in practice humans cannot reliably compare height of things that does not stand on the same level.