For example, if you are telling a story about how one of the slices is much bigger than the other ones, pie (and donut) charts, are a very effective and visually interesting way to tell that story. The other case where I like pie charts (and I do prefer donuts btw) is when the data isn't very accurate and "hiding" some of the detail is actually a better representation of reality.
So yeah, pick the chart that works best for the situation (and if possible, give multiple options), but I do not agree with writing off the whole chart type. Radar charts are more questionable imo haha.
Data visualization is in essence trading accuracy for readability, how much you want and need depends on the goal, audience and data.
[1] https://www.linkedin.com/posts/jameseagle_mobilephones-datav...
So is a stacked bar chart.
I am a big advocate or arranging the pie slices in order (largest to smallest, or smallest to largest).
I also really recommend The Wall Street Journal Guide to Information Graphics: The Dos and Don'ts of Presenting Data, Facts, and Figures https://www.amazon.com/Street-Journal-Guide-Information-Grap...
That pie chart tells me that the slices are approximately the same, which is a useful message to effectively deliver visually. Pie charts are great for understanding relative value.
Divining or comparing the precise values is not a good use for it.
Showing how domanant one factor is.
Showing how no factor is dominant.
[1] https://www.ft.com/__origami/service/image/v2/images/raw/htt...
[2] https://blogs.ft.com/the-world/files/2017/09/bar-chart.png
Any chart format has a set of data for which it's a terrible fit. Different formats have different information optimized to communicate at a glance, and if you're deliberately using the wrong one, you'll end up with a bad graph; that's not a takedown of the format itself.
People don't want accuracy.
People don't want details.
People want pretty.
They will reject any other type of plot that is better than pie charts on the other two metrics.
Hence, pie chart.
The higher up you go, the more important the appearance is, and the less important the details are. The role of most presentations is not to get people to understand, but to impress. Senior folks have given feedback that "Your presentation slides don't have enough details. If you make it easy for the audience to understand, they will undervalue your work."
If I add percentages or values to the chart, there are no issues with either interpretation or comprehension. The pie chart is just a visually pleasant way to display data compared to, say, a table or a bar chart. Data that's displayed in a boring is quickly forgotten, but data presented in a striking way will help your point being remembered. It's akin to rhetoric/style in writing. You can write in a matter-of-fact descriptive way and bore 90% of readers to death, or you can articulate your point with striking metaphors, rhythm, etc... and make an impact.
This is an issue that I often notice with engineers. They assume that communication is transparent. A five page long table of figures? Sure! A front-end with tons of buttons, slide bars for every adjustable parameters and a full report of everything going on under the hood? Who wouldn't want that!
There's nothing wrong with pretty. You don't always have to sacrifice accuracy to get pretty. And pretty ensures that your accurate data isn't ignored.
If you add numbers to the pie chart, then you don't need the chart at all. The benefit of a bar chart is that you don't need to list the individual percentages. At a quick glance, you can get more information from a bar chart than you can from a pie chart.
But if you're not trying to convey details, a pie chart is prettier.
Oftentimes they will be labelled as well with the exact percentage numbers which helps. It's not really a scientific visualization tool, but it adds punch to a presentation when you want to show that one or more subsegments of a whole really dominate the rest.
The article then poses the question "Let’s See if it actually rains more on the weekend." Looking at the pie chart, it's immediately obvious at a glance, that YES, it does rain more at the weekend, as the two segments for Saturday and Sunday together account for nearly half the pie. Clearly the pie chart is perfect for answering this question. But then, the article launches into a whole spiel about how pie charts are useless because you can't tell which was rainier between Saturday or Sunday.
However, if you used an alternative presentation e.g. the lollipop charts as they suggest, then it's NOT obvious for answering the question of whether the 2 weekend days rained more or less than the 5 other days. Rather it's benefit is in determining which days were the rainiest.
The obvious take-home is to use the appropriate graph to illustrate the conclusion you're trying to make from the data, but also include the raw data so that others can analyse it if they think there might be other details that are important.
So what the author wants to see is if both Saturday and Sunday are rainier than any other week. So the problem isn't that you can't differentiate between those two days, but that you can't between either of those days individually and Monday.
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- Stephen Few, August 2007
Also, engineers are notoriously bad at making visualizations. Sorry if this offends you. I would recommend everyone here spend some time looking at pretty visualizations and maybe reading about it
No sane person who cares about data-driven decisions uses piecharts.
That said, they are more of an inspiration than a practical handbook of templates to make your own visualization.
