Bubble Chart Guide
When to use a bubble chart
A bubble chart displays a set of numeric values as a circles. It is especially useful for data sets with dozens to hundreds of values, or when the values differe by several orders of magnitude.
How our bubble chart works
The circles in a bubble chart represent different data values, with the area of a circle corresponding to the value. The positions of the bubbles don't mean anything, but are designed to pack the circles together with relatively little wasted space.
Because a bubble chart uses area to represent numbers, it is best for positive values. If your data set includes negative values, they will be shown in a different color: a circle for 100 and a circle for -100 will both be the same size, but 100 will be blue and -100 will be red. If your data set has many negative numbers, you might consider a block histogram instead.
To see the exact value of a circle on the chart, move your mouse over it. If you are charting more than one dimension, use the menu to choose which dimension to show. If your data set has multiple numeric columns, you can choose which column to base the circle sizes on by using the menu at the bottom of the chart.
To highlight a circle, click it and it will turn orange. To remove the highlight, just click again. To highlight more than one circle use control-clicks. The bubble chart will display the sum of the values of all the highlighted circles. The highlights are also useful for following a particular set of items as you switch between numeric columns. And your highlights will be saved with any comments you make, so you can easily refer to particular parts of the histogram.Data requirements
Our bubble chart takes a table with one text column, for labels, and one or more numeric value columns, to create the chart. For instance, in the table below "Condition" is the label column and "Number of people infected" is the value column.
| Condition | Number of people infected |
|---|---|
| Incurable Optimism | 1,000,000 |
| Attack of Giggles | 50,000 |
| Unexplained Smiling | 6,000 |
Expert notes
Bubble charts are unusual, but have advantages. They can legibly show data values that differ by a ratio of 100,000, and can display hundreds of individual values at once. You can think of them as performing a visual square-root transform on the data set.