> it's worse than a pie chart because visually it's much harder to compare sizes of horizontal and vertical rectangles
Research I've seen suggests the exact opposite -- that people are great at estimating area of rectangles, and terrible at estimating area of circular or triangular shapes. They know which circle is bigger, but don't have any idea by how much bigger.
That said, pie chart slices work for simple data not because of area, but because all you have to compare is the simple length of the circumference segments. That's a single dimension, and easy to compare.
Unfortunately, as this cell phone OS chart is trying to support comparison of multiple sets and subsets, circumference segments alone are inadequate to convey the relative sizes of the sets.
The more complex the information, the more the usefulness of the nested rectangles versus pie chart slices becomes clear. Imagine for example a visual representation of drive space usage by directory and subdirectory.
Here is a drive space chart using nested rectangles:
In fact, if you use both apps, you'll see DaisyDisk is not able to give you the "grand perspective" in a single view, it requires clicking to zoom in on a slice it then expands to a full pie to drill down.
I'm not suggesting circles of different sizes instead of rectangles, which is what this study is about. While interesting, it's not relevant to my statement.
> That said, pie chart slices work for simple data not because of area, but because all you have to compare is the simple length of the circumference segments. That's a single dimension, and easy to compare.
Big whatever to taht. It's easier to compare a pie chart than rectangles of varying orientations, which is my point. I don't really care if it's because it's a linear measurement vs an area derived from a linear measurement. Let's be pedantic, shall we?
If you're interested in comparing the various market shares, a simple bar chart is much easier to understand, just look at which one is taller.
With these rectangle/tree map things, I never know what to think: well this one is wider, but this other one is taller; you have to do multiplication just to compare 2 market shares.
This diagram is a collection of bar charts. One bar chart running horizontally, showing OS, the other bar chart(s) vertical, showing manufacturers within an OS. It could be disassembled, certainly, but then doesn't as readily show the sets and subsets of who has how much relative share of the whole.
Research I've seen suggests the exact opposite -- that people are great at estimating area of rectangles, and terrible at estimating area of circular or triangular shapes. They know which circle is bigger, but don't have any idea by how much bigger.
That said, pie chart slices work for simple data not because of area, but because all you have to compare is the simple length of the circumference segments. That's a single dimension, and easy to compare.
See "Pizzas: or Square? Psychophysical Biases in Area Comparisons", http://groups.haas.berkeley.edu/marketing/PAPERS/PRIYA/p5.pd... for how people lean on a single dimension for size or area comparisons.
Unfortunately, as this cell phone OS chart is trying to support comparison of multiple sets and subsets, circumference segments alone are inadequate to convey the relative sizes of the sets.
The more complex the information, the more the usefulness of the nested rectangles versus pie chart slices becomes clear. Imagine for example a visual representation of drive space usage by directory and subdirectory.
Here is a drive space chart using nested rectangles:
http://grandperspectiv.sourceforge.net/ScreenShots/1_0-Folde...
For comparison, here is an attempt do do the same using pie charts:
http://www.daisydiskapp.com/img/d4.png
In fact, if you use both apps, you'll see DaisyDisk is not able to give you the "grand perspective" in a single view, it requires clicking to zoom in on a slice it then expands to a full pie to drill down.