Response to, agree, disagree in 50 words or more.
Pie charts show parts of a whole. To do a pie chart, you need to know 100 percent of something. For example, if you knew that a senator’s staff budget was $1 million per year, a pie chart could indicate how that breaks down, such as x-amount toward salaries, x- amount toward mailings, x-amount toward town meetings. The general rule of thumb – for pies and bars – is that if there are more than five or six divisions, the chart becomes too difficult to read and the information is better used as a list.
In general, if the pie is truly a visual element, indicating clearly the division of something – such as 50 percent of the senator’s budget going toward salaries – you don’t need to put the percentage on the pie labels. You could relay more information by putting the actual number, such as $450,000. Sometimes we do that, and sometimes we put both numbers on (percentage and actual), but we then run the risk of overwhelming the reader with stats.
Another version of a pie chart is called a stack chart or a sheet cake. Every year we run the dollar bill and show what portion of it goes where in the federal budget. That’s really a pie in a rectangle shape.