This morning I came across this >article
I find it difficult to believe that an organisation so intrinsically linked with data as Nelsen can fall into one of the biggest visualisation traps around. Their site states, “We believe providing our clients a precise understanding of the consumer is the key to making the right decisions.” I seriously doubt any reader of the following diagram will receive an accurate impression.
In fact the area method is far from perfect, notice how difficult it is to compare values of 19 and 20? Had the percentages not been shown we may have assumed they were identical. The bar method is far superior for communicating quantities precisely. Chapter 1 of my dissertation from last year examines this in greater detail.
Nelsen are currently running a data visualisation competition, unfortunately only residents of the United States are permitted to enter. Nonetheless I await the results with bated breath.