In Credit Suisse’s report entitled Global Wealth Report 2011 (PDF), a pyramid chart is used to visualize the number of high wealth individuals.
My view on pyramid charts is quite simple. It’s hard to see which portion is larger than the other. A good example of this visual challenge is the layer representing the USD 5 to 10 Million bracket and the layer representing the USD 10 to 100 million bracket. At a glance, I instinctively think the USD 10 to 100 million is roughly equal to the USD 5 to 10 million. However, looking at the actual values, the USD 10 to 100 million layer is roughly half the size.
This visual inaccuracy is due largely because humans are really bad at comparing areas. It’s the main reason why pyramid charts fail as a data visualization in most cases.
You’ll also notice that the cap does not represent the actual percentage of the pyramid; i.e. those with more than 100 million USD make up less than 1% of the entire group. That cap is definitely not 1 percent of the pyramid.
Note that I do understand the analogy being represented here; the uber-wealthy are at the top of the pyramid. However, if this data is important to understand, you really should use the tried and tested bar chart as shown below.
Data visualization of wealth distribution using a bar chart
No comments have been posted yet.