Area Graphs

Area Graphs can be used to:

Displaying changes in cumulative value or percentage over time
Comparing groups on outcome measurements
Display group trends

Area Graphs combine the features of Line graphs (refer to "Line Graphs") and Stacked Bar graphs (refer to "Stacked Bar Graphs"). They look like someone took a Line graph and colored in the areas underneath each line. But each of these area segments are stacked on top of each other, like in a Stacked Bar graph. Thus, the total size of the area at each category reflects the cumulative value of all data items in that category.

Each data series in the graph corresponds to a colored segment of the total area. The first series will always be the top area segment.

Example 13.9 below shows how Area graphs work.

Area Graphs are useful when you want to show group trends in addition to comparing trends between individual series of data. For instance, Example 13.9 shows year-by-year trends in overall market penetration for a certain type of product. At the same time, it breaks down market penetration by brand, with each area segment revealing year-by-year market penetration trends for a different brand.

Area graphs are in the Standard Data Class (see Chapter 12 for details). To create an Area graph with PopChart XML, create a Graph element and set its Type attribute to Area, as shown in the example below.