Apply the self-sufficiency test to this chart. Wish away the printed data. Now, does the chart convey any message? Where is the data embedded? Is it in the white dot, the black dot, the gold ring, the gold disc, the black ring, the eye-white? All of the above?
Now, do the same test on this chart (I removed the sales data, replacing it with years):
How would one compare the white to the orange? If one measures the lengths of the sides, the ratio of white to orange is about 1.32. If one compares areas of the squares, then the ratio is 1.73. Note that this requires the reader to see through the orange area to size up the area of the large white square. Alternatively, we can compute the ratio of the white area as observed to the orange square, and that ratio is 0.73.
The real ratio between 1980 and 2010 sales is given as 3.9/2.7 = 1.44. Given rounding errors, it seems like the designer may have used a ratio of lengths of the sides.
The problem is the same whether sides or areas are used. Can the reader figure out that the 1980 sales is about 40% higher than the 2010 sales?
I suspect that most of us react primarily to the visible areas, which means that we'd have gotten the direction of the change wrong, let alone the magnitude.
Craig really dislikes this one. It's a variant of the racetrack chart. As any athlete knows, inner tracks are shorter than outer tracks. Could it be that days have gotten longer in the last 30 years? Apparently, the editors at Fast Company think so.