Bubble charts are an evolution of the point chart. By being able to modify the size of the point (bubble in this case) we can visualize one more dimension for our data. Actually, by adding colors to the bubble and a legend (a legend contains a list of the variables appearing in the chart and an example of their appearance) you could even visualize four dimensions. An example of using the bubble chart would be to plot the impact of education on the salary over the years between United States, China, and Russia. The x axis would represent the years, the y axis would be the salaries, the size of the bubbles would be degree of education (bigger being having more education), and the colors would represent the countries. This is depicted in the following figure:
Take a look at the files in the Bubble Chart
folder in the code files downloadable from www.packtpub.com. This chart will also use horizontal and vertical axes so it might be good to read Chapter 1, Getting...