> 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 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.
> 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.
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.