The challenge of using area to communicate values in visualizations

Bubble charts are a popular way to present quantitative data. Often the area of the circles in the bubble chart are used to encode the value of a parameter. The larger the value, the greater the area, the bigger the circle. This makes intuitive sense and can be quite effective for rough comparisons. However, it is important to understand that we are not very good at estimating area and  these representations distorts the data because we are not very good at estimating area.
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