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Comment by Roridge | Hacker News Reader

uh... why? I could see that the red part was bigger than the blue part.

THAT Pie chart was bad because of the legend being self representational, not the isometric projection.

I think his point is that when you include the pixels which represent the thickness of the disc, you inflate the apparent size of that slice.

So while you can clearly see the size of the elements, it requires thought and interpretation. Compare to a 2D flat chart, which is very clear although not so pretty. Shouldn't a visualisation require as little thought as possible?

I blame PowerPoint.

I actually got the point, I was saying that it was still obvious which part was bigger, which is what a pie chart should be used for. Anything more complex than that, and it's being used incorrectly.

The whole point of a chart is at-a-glance understanding of numbers and stats that would normally take a more careful once-over.

And the whole point of a pie chart is to use one thing -- the size of a slice -- to represent a single datum.

A 3d pie chart muddles both of those things for form-over-function reasons. How is this even contentious? Pie charts are notoriously bad anyway, especially if there's not a huge difference between the data points. This makes them notably worse.

yeah... I get it... I could still see which part was bigger.

The purpose of a pie chart isn't to show which is bigger (which is much easier to convey in text), but to give relative proportions.

So could you accurately estimate the two sizes? Research suggests you'd be better off with a bar chart than with a pie chart except in certain cases (25% vs 75%) and that isometric pie charts are worse than flat ones.

It would be just as trivial to create a 3D bar chart that has the same effect as the example (accurate, self-referential, and confusing because of the color/label mismatch). While clever, this example isn't an indictment of pie charts, because it clearly shows the relative proportions of two quantities (as would a bar chart).

There's two different links in these comments that explain at length why pie charts do not clearly show relative proportion. This is even less true of 3D pies.

Honestly, I always find split bars easier to read in terms of proportions than a pie. The human mind is better at estimating linear distances than angles.

Not to mention with split bars you can more easily show the proportional change of things over another axis (usually time).

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