As I mentioned in my first post, this graph is terrible. I can guess that in a bewildered state, you are wondering “How can that be? I’ve seen that chart hundreds of times”. The problem is people have trouble reading pie charts. It is true that by presenting data in a pie, the reader intuitively understands that you are showing them the pieces that compose a portfolio; however, you’re going against the limitations of human perceptions. We are very good at comparing one dimension, but our facilities quickly diminishes when trying to compare 2 or more dimensions. That’s what you’re doing when generating a pie chart. You’re forcing the reader to compare multiple dimensions at once.
This limitation is very well known in the academic field of data visualization. If you have any doubts, take a look at the wonderfully complete discussion of pie chart limitations by the data visualization expert Stephen Few titled “Save the Pies for Dessert“.
It’s fairly simple to avoid pie chart shortcomings by showing the sector composition in columnar bar chart. With the graph below, the user can visualize the composition by comparing a single dimension, height.