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Should I use a pie chart?

shouldiuseapiechart.com

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Re: Should I use a pie chart?

#21

Post by _dain_ »

chefandy wrote: post #13
navls wrote: post #6

I wasn't aware they were controversial. I had to google to find some arguments against pie charts https://www.data-to-viz.com/caveat/pie.html

Even then, it's pretty ridiculous to say that this is a valid argument against using pie charts. It's a valid argument against using them when you've got multiple similarly sized slices, or some other thing that would make them the wrong choice, but there are great reasons to not use most visualizations in incompatible contexts. Just like anything else in graphic design, these things should be used when they are bett…

pie charts really are inferior in practically every context though.

Re: Should I use a pie chart?

#22

Post by karaterobot »

I went looking for the famous Edward Tufte quote about pie charts, Tufte being one of the elder statesmen of data visualization, and found it at this old HN thread:

https://news.ycombinator.com/item?id=2991062

  A table is nearly always better than a dumb pie chart; the
  only worse design than a pie chart is several of them, for 
  then the viewer is asked to compare quantities located in 
  spatial disarray both within and between charts [...] Given 
  their low density and failure to order numbers along a     
  visual dimension, pie charts should never be used.

Re: Should I use a pie chart?

#23

Post by chefandy »

PheonixPharts wrote: post #17
navls wrote: post #6

I wasn't aware they were controversial. I had to google to find some arguments against pie charts https://www.data-to-viz.com/caveat/pie.html

> I had to google to find some arguments against pie charts Can you give me any arguments for pie charts? I also disagree with that article that the best alternative to a pie chart is a bar chart. Whenever your doing any sort of data visualization you should always ask "How does this representation convey information that cannot be represented in a table ?" Can you provide an example where a pie chart would tell you…

Charts are useful for quickly conveying relationships within data, not for presenting data as raw information. They're useful specifically because they're not extremely information dense. If you're making video media, an article, an infographic, a poster, slides for a presentation, or anything similar, tables usually have far less impact and don't convey relationships and context well. Whether charts are the right tool for the job is a communication question. What are you trying to communicate, why, to whom, and in what context? While it perennially annoys the hell out of many in the engineering mindset, people find strategies that take these distinctions into account valuable, and that's why visual designers exist.

Re: Should I use a pie chart?

#24

Post by chefandy »

PheonixPharts wrote: post #18
chefandy wrote: post #13

Earlier quoted context omitted.

Even then, it's pretty ridiculous to say that this is a valid argument against using pie charts. It's a valid argument against using them when you've got multiple similarly sized slices, or some other thing that would make them the wrong choice, but there are great reasons to not use most visualizations in incompatible contexts. Just like anything else in graphic design, these things should be used when they are bett…

Can you give me a single example where a pie chart would better convey information than a table? The only visualization more useless than a pie-chart is a 3d pie-chart.

See my response to your comment above. You're ignoring the reason data visualizations exist in the first place.

Re: Should I use a pie chart?

#25

Post by _dain_ »

PheonixPharts wrote: post #18
chefandy wrote: post #13

Earlier quoted context omitted.

Even then, it's pretty ridiculous to say that this is a valid argument against using pie charts. It's a valid argument against using them when you've got multiple similarly sized slices, or some other thing that would make them the wrong choice, but there are great reasons to not use most visualizations in incompatible contexts. Just like anything else in graphic design, these things should be used when they are bett…

Can you give me a single example where a pie chart would better convey information than a table? The only visualization more useless than a pie-chart is a 3d pie-chart.

>Can you give me a single example where a pie chart would better convey information than a table?

there's a specific type of pie chart that's good: a "clock chart".

this is when you're depicting how long some contiguous sequence of events took as a fraction of a whole duration. you map the start and end to the 12 o'clock position, and the intervening ones wrap around clockwise.

e.g. the history of the universe with the big bang at the top, then formation of stars, galaxies, planet earth, dinoaurs etc as you go around clockwise. then human history is a tiny slice at like 30 seconds to midnight or whatever it is.

this works because it piggybacks on people's existing strong spatio-temporal intuition for clock faces. time is a flat circle.

Re: Should I use a pie chart?

#26

Post by xnx »

I like 2 slice pie charts for data where those 2 pieces encompass the whole. Bar charts are superior in every other way (3+ segments, easier to compare, etc.), but are not as good at conveying you're looking at the total.

Re: Should I use a pie chart?

#27

Post by PheonixPharts »

_dain_ wrote: post #25
PheonixPharts wrote: post #18

Earlier quoted context omitted.

Can you give me a single example where a pie chart would better convey information than a table? The only visualization more useless than a pie-chart is a 3d pie-chart.

>Can you give me a single example where a pie chart would better convey information than a table? there's a specific type of pie chart that's good: a "clock chart". this is when you're depicting how long some contiguous sequence of events took as a fraction of a whole duration. you map the start and end to the 12 o'clock position, and the intervening ones wrap around clockwise. e.g. the history of the universe with t…

I'll concede that this is a reasonable case.

Re: Should I use a pie chart?

#28

Post by PheonixPharts »

chefandy wrote: post #23
PheonixPharts wrote: post #17

Earlier quoted context omitted.

> I had to google to find some arguments against pie charts Can you give me any arguments for pie charts? I also disagree with that article that the best alternative to a pie chart is a bar chart. Whenever your doing any sort of data visualization you should always ask "How does this representation convey information that cannot be represented in a table ?" Can you provide an example where a pie chart would tell you…

Charts are useful for quickly conveying relationships within data, not for presenting data as raw information. They're useful specifically because they're not extremely information dense. If you're making video media, an article, an infographic, a poster, slides for a presentation, or anything similar, tables usually have far less impact and don't convey relationships and context well. Whether charts are the right to…

> Charts

To be clear, I'm specifically talking about pie-charts and not all charts. There are plenty of cases where a chart conveys information appropriate to the task.

The relationships are visually represented in a table, the minimum table being just a vertical list. A table can be more, but it isn't required. Additionally the relationships in a table are more clearly represented in most all cases.

Information density also doesn't imply that you most be conveying a lot of information, it relates to the efficiency of your use of visual space.

There are no instances (aside for the other example of a clock plot) where the relationships in your data (since you don't want to use information) are not more clearly conveyed with a list then a pie chart.

> and that's why visual designers exist.

I've spent quite a bit of time working with and talking to visual designers and have yet to meet one who think pie-charts are an effective tool for visual communication.

Re: Should I use a pie chart?

#29

Post by PheonixPharts »

ggregoire wrote: post #16
navls wrote: post #6

I wasn't aware they were controversial. I had to google to find some arguments against pie charts https://www.data-to-viz.com/caveat/pie.html

> In the adjacent pie chart, try to figure out which group is the biggest one [...]. You will probably struggle to do so and this is why pie charts must be avoided. It's not that bad when the purpose of the pie is not to figure out which group is the biggest. I find the pie pretty appropriate when the goal is to figure out - if all the groups are more or less the same - if one or several groups are way bigger than th…

> It's not that bad when the purpose of the pie is not to figure out which group is the biggest

But it's not better than a sorted table:

- A (90%)

- B (5.1%)

- C (4.9%)

Which group there is biggest? Which is the smallest?

> why would you not order them already inside the chart?

What's the implicit ordering of a pie chart? It's not hard to define one that makes sense (start at midnight) but it's not implicit in the chart, it needs to be explained to the viewer. Since similar sized portions of the chart are hard to distinguish, there's no way to be visually certain that you are correctly understanding the ordering.

Re: Should I use a pie chart?

#30

Post by PheonixPharts »

chefandy wrote: post #24
PheonixPharts wrote: post #18

Earlier quoted context omitted.

Can you give me a single example where a pie chart would better convey information than a table? The only visualization more useless than a pie-chart is a 3d pie-chart.

See my response to your comment above. You're ignoring the reason data visualizations exist in the first place.

> You're ignoring the reason data visualizations exist in the first place.

My opinion on pie-charts and poor visualization comes from years of studying data visualization, not ignoring it. Would you argue that Tufte doesn't value data visualization since he holds the same views?

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