|Microsoft Office Excel 2003
Microsoft Excel 2002
A Bubble chart is a variation of a Scatter chart in which the data points (data points: Individual values plotted in a chart and represented by bars, columns, lines, pie or doughnut slices, dots, and various other shapes called data markers. Data markers of the same color constitute a data series.) are replaced with bubbles. A Bubble chart can be used instead of a Scatter chart if your data has three data series (data series: Related data points that are plotted in a chart. Each data series in a chart has a unique color or pattern and is represented in the chart legend. You can plot one or more data series in a chart. Pie charts have only one data series.), each of which contains a set of values. For example, the worksheet in the following picture contains values for three types of data: number of products, dollar value of sales, and percentage size of market share.
In a Bubble chart, the size of the bubbles is determined by the values in the third data series. For example, the following Bubble chart displays bubble sizes that correspond to the values in the third column of the sample data (Market share %).
Notice that the data in this Bubble chart is plotted as follows:
- Number of products is displayed along the horizontal (x) axis.
- Sales amounts are displayed along the vertical (y) axis.
- Market share percentages are represented by the size of the bubbles.
When to use a Bubble chart
Bubble charts are often used to present financial data. Use a Bubble chart when you want specific values to be more visually represented in your chart by different bubble sizes. Bubble charts are useful when your worksheet has any of the following types of data:
- Three values per data point Three values are required for each bubble. These values can be in rows or columns on the worksheet, but they must be in the following order: x value, y value, and then size value.
- Negative values Bubble sizes can represent negative values, although negative bubbles do not display in the chart by default. You can choose to display them by formatting that data series. When they are displayed, bubbles with negative values are colored white (which cannot be modified) and the size is based on their absolute value. Even though the size of negative bubbles is based on a positive value, their data labels will show the true negative value.
- Multiple data series Plotting multiple data series in a Bubble chart (multiple bubble series) is similar to plotting multiple data series in a Scatter chart (multiple scatter series). While Scatter charts use a single set of x values and multiple sets of y values, Bubble charts use a single set of x values and multiple sets of both y values and size values.
Create a Bubble chart
- Select the data you want to display in the Bubble chart.
Note It's best not to include row or column headings in the selection. If you select the headings with your data, the chart may produce incorrect results.
- On the Insert menu, click Chart.
- In the Chart type box, click Bubble.
- Under Chart sub-type, click the chart sub-type you want to use.
For a quick preview of the chart you are creating, click Press and Hold to View Sample.
- Click Next, and continue with steps 2 through 4 of the Chart Wizard.
For help on any of the steps, click the question mark (?) on the Chart Wizard title bar.
- Smaller bubbles may be hidden by larger bubbles, making it seem that Excel has not drawn all of the data markers.
- When an entire data series contains negative bubble sizes, the series is not displayed by default. If you want to see the negative bubbles, select the series you want in the Chart Objects list on the Chart toolbar, and then click Format Data Series on the same toolbar. On the Options tab, select the Show Negative Bubbles check box.
Formatting Bubble charts
There are several ways to change the format of a Bubble chart:
- Display bubbles with a 3-D visual effect By selecting the 3-D Bubble chart sub-type, bubbles are formatted with a 3-D visual appearance.
Note A 3-D Bubble chart is 3-D in appearance only — it actually remains a 2-D chart type. Unlike other 2-D chart types, however, this chart type cannot be used in a combination chart.
- Adjust the size of bubbles The size of the bubbles can represent the area of the bubbles or the width of the bubble, which affects the relative size of one bubble to another. For example, you can use the Area of bubbles option if you are charting rental costs of apartments for which you know the specific square footage (such as 1,700 square feet). The Width of bubbles option can be used for representations such as market share between products.
You can also scale the bubble size for a data series by specifying a percentage between 0 and 300 — the larger the percentage, the larger the bubbles.
- Display error bars To graphically express potential error amounts relative to each bubble in a bubble series, you can display error bars for the X values, the Y values, or both.
- Change the color and fill effects of bubbles You can assign different colors and fill effects (such as pattern, texture, and gradient) to individual bubbles or an entire bubble series.
- Replace bubbles with pictures You can replace each bubble or all bubbles in a series with a picture. The size of the picture is automatically adjusted to match the bubble size for each corresponding value.
Change the color and pattern of bubbles
- In the Bubble chart, select a bubble or bubble series.
- On the Format menu, click Selected Data Point or Selected Data Series.
- On the Pattern tab, select the options you want.
- To change the gradient, texture, or pattern of bubbles, click Fill Effects, and then select the options you want on the Gradient, Texture, or Pattern tab.
To use pictures instead of bubbles, click the Picture tab, and then click Select Picture to insert the picture you want.