Essential Graphing • Bubble Plots • Additional Examples of the Bubble Plot Platform
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Additional Examples of the Bubble Plot Platform
The following examples further illustrate the features of the Bubble Plot platform.
Example of Specifying Only a Time Variable
For dynamic bubble plots, you might specify only a Time variable and no ID variable. The resulting bubble plot contains a single moving bubble that tracks the series as the Time value changes.
1.
Select Help > Sample Data Library and open PopAgeGroup.jmp.
2.
Select Graph > Bubble Plot.
3.
Select Portion60+ and click Y.
4.
Select Portion 0-19 and click X.
5.
Select Year and click Time.
6.
Select Region and click Coloring.
7.
Click OK.
The initial report window appears.
The Initial Report Window with a Time Variable
8.
Click on the bubble to select it.
All rows in the data table are also highlighted.
9.
From the red triangle menu, select Trail Bubbles > All and Trail Lines > All.
10.
Click the play button.
The bubble plot animates, showing a trail for the single bubble.
Animated Bubble Plot over Time
Example of Specifying Only ID Variables and Splitting a Bubble
For static bubble plots, you might specify one or two ID variables and no Time variable. The resulting bubble plot contains a bubble at each ID value. Note that although this bubble plot is static, you can perform splitting on bubbles.
1.
Select Help > Sample Data Library and open PopAgeGroup.jmp.
2.
Select Graph > Bubble Plot.
3.
Select Portion60+ and click Y.
4.
Select Portion 0-19 and click X.
5.
Select Region and Country and click ID.
6.
Select Region and click Coloring.
7.
Click OK.
The initial report window appears.
Initial Report Window with ID Variables
Split the bubble representing the region of North America into countries.
8.
Click on the bubble representing North America (hover over a bubble to see its label, or use the legend to find the color of North America.)
9.
Click Split.
You see that the North America bubble has split into three bubbles, representing the countries within the region of North America (the United States of America, Canada, and Mexico).
Splitting the North America Bubble
Example of a Static Bubble Plot
This example uses the SATByYear.jmp sample data table, which contains SAT verbal and math test scores for a selection of the US population in 2004.
1.
Select Help > Sample Data Library and open SATByYear.jmp.
2.
Select Graph > Bubble Plot.
3.
Select SAT Verbal and click Y.
4.
Select SAT Math and click X.
5.
Select State and click ID.
6.
Select % Taking (2004) and click Sizes.
7.
Click OK.
The report window appears.
The Static Bubble Plot Report Window
From The Static Bubble Plot Report Window, you draw the following conclusions:
•
Higher verbal scores appear to be associated with higher math scores, since the two track very closely in the bubble plot. This signifies a correlation between verbal and math scores.
•
The larger bubbles represent the US states that have a high percentage of individuals taking the SAT test in 2004. These larger bubbles are all grouped together in the lower left of the graph. This shows that when a state has a high percentage of individuals taking the test, both the math and verbal scores are low.
Instead of grouping the bubbles primarily by state, group the bubbles primarily by region as follows:
1.
From the red triangle menu, select Show Roles.
2.
Click on the ID link.
3.
Select Region, and click OK.
Region is now the primary ID variable.
4.
Click on the ID2 link.
5.
Select State, and click OK.
State is now the secondary ID variable.
Example of Bubble Plot Grouped by Region and State
6.
Click on the bubble that represents the Southwest region (hover over a bubble or click on it to see its label).
7.
Click Split.
Now the bubbles are split by the secondary ID variable, which is State. You now see each state within the Southwest region.
Example of Southwest Region Split by State
From Example of Southwest Region Split by State, you see that there is significant variation between the scores from the Southwest states.
8.
Click Combine to combine the southwest states again.
9.
To do a comparison, click on the New England bubble (hover over a bubble or click on it to see its label).
10.
Click Split.
Example of New England Region Split by State
You see that the New England states do not have as much variation as the Southwest states.
Example of a Bubble Plot with a Categorical Y Variable
All of the examples shown so far use continuous Y variables. If you use a categorical (nominal or ordinal) Y variable, the bubble plot appears differently.
This example uses the blsPriceData.jmp sample data table, which shows the price of commodities over several years. Because the value of the US dollar changes over time, a column named Price/Price2000 shows the ratio of a commodity’s price at any given time to the price in the year 2000.
1.
Select Help > Sample Data Library and open blsPriceData.jmp.
2.
Select Graph > Bubble Plot.
3.
Select Series and click Y.
4.
Select Price/Price2000 and click X.
5.
Select date and click Time.
6.
Click OK.
The report window appears.
This produces a bubble plot that, when animated by clicking the play button, shows the price bubbles moving side to side according to their price ratio.
Static Example of Animated Bubbles
For easier readability, add grid lines as follows:
7.
Double-click on the categorical axis.
8.
In the Y Axis Specification window, select the box under Gridline next to Major.
9.
Click OK.
To animate the bubble plot, click the play button. The price bubbles move side to side, according to their price ratio.