By default, all bubbles are scaled according to the size of the plot area.
Bubble charts can facilitate the understanding of social, economical, medical, and other scientific relationships.
According to Berman (2007), bubble charts can "be used in project management to compare the risk and reward among projects. In a chart each project can be respresented by a bubble,the axis can represent the net present value and probability of success and the size of the bubble can represent the overall cost of the project".
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