Fig. 18.1.6 Number chart.Pie Charts
Pie charts have been around for hundreds of years to show parts of a total relationship
over a static period of time (such as a slice of the pie vs. the whole pie). Pie charts are a
simple way to visualize simple comparisons for a single category; however, they do not
work well to compare the size or segment across multiple pie charts. A pie chart splits a
population of data for a single category into segments, and the total of all the segments
equals 100%. If there are too many segments, then pie charts do not work well as they
can be difficult to label or to show the difference in proportions. Also, a pie chart can
take a lot of space on a dashboard or report. Fig. 18.1.7 shows an example of a pie chart
where the category is ratings for a hotel. Ratings are segmented 1 through 5, and the pie
chart shows the percentage of each segment.
Chapter 18.1: An Introduction to Data Visualizations