Basic Analysis and Graphing - SAS

Chapter 19 Creating Tree Maps 467
Example of Tree Maps
Example of Tree Maps
Tree maps can be useful in cases where histograms or bar charts are ineffective. This example uses the
Cities.jmp sample data table, which contains meteorological and demographic statistics for 52 cities.
Compare the bar chart to the tree map.
Create a bar chart representing ozone levels in each of the 52 cities:
1. Open the Cities.jmp sample data table.
2. Select Graph > Chart.
The launch window appears.
3. Select OZONE and click Statistics.
4. Select Mean.
5. Select city and click Categories, X, Levels.
6. Click OK.
The report window appears.
Figure 19.2 Ozone Levels in a Bar Chart
Although it is easy to see that there is a single large measurement, each bar looks similar. Subtle distinctions
are difficult to see.
Create a tree map representing ozone levels in each of the 52 cities:
1. Return to the Cities.jmp sample data table.
2. Select Graph > Tree Map.
The launch window appears.
3. Select POP (population) and click Sizes.
4. Select city and click Categories.