Bubble graph application in data analysis: 

An Interactive Bubble Graph widget is a conventional bubble plot that allows you to visualize the trends of three different metrics for a set of attribute elements. The data structure for an Interactive Bubble Graph widget is very specific. At minimum, one attribute and three metrics are required. In the bubble graph:

·          

·         One bubble is displayed for each attribute element.

·         Each bubble's position on the X-axis represents the value of the first metric.

·         Each bubble's position on the Y-axis represents the value of the second metric.

·         The size of each bubble represents the value of the third metric.

Why do we use bubble graph?

Bubble graph helps you to represent specific values by different bubble size. 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 and 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. 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 is similar to plotting multiple data series in a Scatter chart. 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.

How to create?

Atleast  4 variables are needed.

• Two - Continuous variables (for x and Y axis)
• One - Continuous variables (for ‘Size of the bubble’)
• One - Category variable

In SPSS tool, navigate to Analyze > Custom table

Drag category variable in rows and drag all the continuous variables in the columns.

Keep that in mind that the variable which is being dragged into the rows section should be a nominal variable, if it is not, change its type to proceed further.

Generally the column in which the values are more deviated becomes the size of the bubble and it is kept in the last column of the table. Once the table is generated with required data it is transferred into an excel and the bubble chart is created.

How do you expand the graph?

Using right click on the chart area, go to format axis and make the reqiored changes in order to increase the visibility of the bubbles if required.