The following table compares market shares of several companies in the computer industry as reported by Gartner, an industry monitor. The table gives the number of computer systems shipped during each...

The following table compares market shares of several companies in the computer industry as reported by Gartner, an industry monitor. The table gives the number of computer systems shipped during each quarter, in thousands.

(a) Summarize these data using both a stacked bar chart (of market share) and a mosaic plot. What message do these plots convey about the changes in market share from 2010 to 2011?

(b) Explain the differences between the two charts. One plot shows a feature of the data that the other does not show. What is it, and why is the difference subtle in this example?