Should I use a pie chart?(shouldiuseapiechart.com) |
Should I use a pie chart?(shouldiuseapiechart.com) |
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 more than could be conveyed in a table?
Tables are incredibly information dense, have an unambiguous ordering and can easily scale to expressing 5-6 dimensions of information in the exact same space that a pie-chart can convey. Tables are limited in that they work best when representing a very small number of observations, but pie-charts and bar-charts share this same problem without any of the benefits of tables.
If a table won't cut it, then you probably have enough data that a scatter plot is your best choice. Scatter plots also can easily handle an extra 2-3 dimensions (color, scale, and shape) of information.
If you click on "chrome" it will drill down and show you a pie chart of chrome versions, same for the operating systems.
The only visualization more useless than a pie-chart is a 3d pie-chart.
https://s3.amazonaws.com/edwardtufte.com/pie_apple_marketsha...
(the green segment is made to look larger than the purple one because of a perspective trick)
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 the other groups
- if one or several groups are way smaller than the other groups
Not saying pies are the best for this (bar charts work well too), just saying it works well.
> try to order them by value
I mean, why would you not order them already inside the chart? So that the reader doesn't have to do it.
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.
When I shop for clothes online, I click through colors and sometimes through photos to see clothes from different angles or zoomed in. It's a sneaky kind of carousel that is actually useful.
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.tl;dr be mindful there's often a better plot to use than a pie chart, but if you want to use a pie chart, go for it.
they have a site dedicated to pie charts but couldn't afford a real circle?
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.
Ok, let's start with the most obvious. How about a chart showing how much of a pie has been eaten? There's a bell curve of useful applications for pie charts that moves away from that, and the shoulders might be pretty tight, but it's absurd to say that's it's simply wrong for all applications. Even all moderately common applications.
> the relationships in a table are more clearly represented in most all cases
Nonsense. It might be easier to compare specific values, but people simply needing to parse a column of digits makes it the wrong choice for many applications. If your communication problem involves communicating values, a table is a great way to go. If your communication problem involves quickly communicating relationships between a handful of elements, a table is the least effective way to do that. Not everybody has a use case for all data that is benefited by seeing precise values. You can't pretend that's not true by just ignoring that other use cases exist, or that other audiences aren't like you. Go ask an investor if they'd always prefer tables to box whisker graphs, or a statistician if they'd always prefer tables to data plots. Similarly, pie charts are great for showing roughly how several elements comprise a whole. If you wanted to show that something used about 21% of the budget, something else used about 29% of the budget, and something else used about 50% of the budget, putting that in a pie chart quickly communicate the relationship between those values far better than putting those values in a table, bar chart, or many other visualizations. The audience matters. That wouldn't be useful to accountants, but it might be useful to give a a company-wide audience a rough idea of why some executive action was enacted, for example. The purpose of data visualizations is to present things in ways that reduce the cognitive load of parsing values while still communicating the overall purpose. A box and whisker graph wouldn't be useful for that visualization. And a to the vast majority of people, table would be less efficient at communicating that idea than a pie chart.
> 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.
Without a specific communication problem to solve, you can't determine what the best use of space is. You're expecting every audience to parse information like you do. You're wrong. That's why visual designers exist. The oft-repeated design maxim of avoiding wasted space is something only non-designers say because it's much easier to gauge and reason about than the most effective use of space. Optimizing for economy of space isn't even useful in many contexts. When the purpose is efficiently communicating something, giving the primary message focus often means giving it a lot of space, be it conceptually or physically.
> 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.
Ok, how about how many slices of pie have been eaten?
> 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.
Frankly, people like you-- really strong opinions on visual design but have never practiced it, don't know the methodologies, don't know what most people's use cases are for data visualizations, and generally don't understand why everybody doesn't like looking at numbers as much as you-- are probably people that most experienced visual designers don't want to talk about charts with. Regardless, you could tell me that everyone you've ever met hated pie charts and that still wouldn't be worth any more in this context than just saying it's your arbitrary preference.
Working as a long-time developer, I did encounter a few tutorial-drunk designers who tried to assert their ideas about proper software development in dev meetings they happened to be at. As a developer, it was always like "ok there fella. We'll take your opinion into account. Now go play in photoshop." It was pretty rare, though. But I'm continually astonished by the number of developers that assume their amazing superpowers of reason and logic make them qualified to tell any credentialed experienced professional how their field works.
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.
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?