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Area charts in Microsoft Excel have the same functionality and purpose as line charts. Values are plotted in such a way to enable the viewer to look at results across categories. The difference is in the effect. Area charts fill the plot area from the plotted points downward. In other words, imagine a line chart in which someone took a crayon and filled in the area from a line down to the category axis, and you have an area chart. What's the big deal about having the areas filled in? Because the area between the lines is filled in, the area chart puts greater emphasis on the magnitude of values, and somewhat less emphasis on the flow of change over time than does the line chart.
Here are the steps to follow to create an area chart:
1. Select your data, including the data categories, all the series, and the headers.
2. Click the Chart Wizard button on the Standard toolbar or choose Insert --> Chart.
The Chart Wizard opens.
3. Select the Area chart type, and select the first subtype (Area).
4. Click Finish.
Figure 1 shows how the chart comes out. This chart shows the number of members of a dance club in three local chapters varies from month to month throughout a year. The months are plotted along the horizontal axis. The series (in this example, the three chapters of the club, Westchester, Putnam, and Dutchess) are present and identified by a legend. An interesting twist with the data used for this particular chart is that none of the series crosses another series. The effect of this is that each series is fully visible.
Figure 1: Displaying data as areas.
Watching out for hidden data
In area charts, you can easily have hidden data points. The areas are not transparent, so if a data point (or more than one point) from one series crosses the range of another series, something gets covered up, as shown in Figure 2.
Figure 2: A data point is hidden.
As you can see in this example, the order in which the series appear, with regard to depth (front to back), makes a difference. Luckily, you can change the order of the series by following these steps:
1. Right-click anywhere in the middle of the visible data series.
2. Select Format Data Series from the pop-up menu.
The Format Data Series dialog box appears.
3. Click the Series Order tab.
4. Use the Move Up or Move Down buttons to change the order of the series.
In this way, the smaller data points can be in front and, therefore, visible.
5. Click OK.
Changing the chart subtype
Area chart subtypes include the typical three: Standard, Stacked, and 100% Stacked, along with a 3-D variation for each of these three main types. These are the same subtypes offered by a line chart, but with an area chart, the 100% Stacked chart is clear and easy to read. Here's how to change the chart to the 100% Stacked subtype, for example:
1. Click on the chart once to select it.
2. Choose Chart --> Chart Type.
The Chart Type dialog box appears.
3. Select the third chart subtype (that is, the third one in the first row of chart subtypes — 100% Stacked Area).
In the Chart Subtype area, you can click on any of the chart illustrations to see the name of that chart subtype displayed below.
4. Click OK.
With all 100% Stacked charts, the upper series is flat along the top of the chart. At least with an area chart, you can get a sense of it being there. In a line chart, you can easily miss seeing the top line in a 100% Stacked chart because the line sits adjacent to the top of the plot area.
In certain situations, switching to a 3-D chart subtype is a good way to improve the readability of your chart. To do so, choose Chart --> Chart Type to display the Chart Type dialog box. Select one of the 3-D subtypes (the lower row of subtypes) and click OK.
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