Bar charts beat pie charts almost every time – I say almost because I am open to being convinced … but I won’t be holding my breath.
Disadvantages of pie charts:
– pie slices ranking is difficult to see even if attempted
– rely on color which is an extra level of mental effort for the viewer to process
– colors are useless if printed in black and white
– difficult to visually assess differences between slices
– 3-D is worse because it literally makes the nearest slice look bigger than it should be
Advantages of bar charts:
– easier to read
– no need for a legend
– we can rank the bars easily and clearly
– easy to visually assess difference
If you google “pie charts” you’ll find a bunch of people ranting far worse than me. Here is a good collation of some of the best arguments.
All that being said, data visualization is a matter of taste and personal preference does come into it. At the end of the day it’s about how best we can communicate our message. I wouldn’t dare say we should never use pie charts but personally I tend to avoid them.
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