Basic Analysis and Graphing - SAS

114 Performing Bivariate Analysis Chapter 4
Histogram Borders
Related Information
• “Fitting Menus” on page 115
Histogram Borders
The Histogram Borders option appends histograms to the x- and y-axes of the scatterplot. You can use the
histograms to visualize the marginal distributions of the X and Y variables.
Figure 4.17 Example of Histogram Borders
Group By
Using the Group By option, you can select a classification (grouping) variable. When a grouping variable is
in effect, the Bivariate platform computes a separate analysis for each level of the grouping variable.
Regression curves or ellipses then appear on the scatterplot. The fit for each level of the grouping variable is
identified beneath the scatterplot, with individual popup menus to save or remove fitting information.
The Group By option is checked in the Fitting menu when a grouping variable is in effect. You can change
the grouping variable by first selecting the Group By option to remove (uncheck) the existing variable.
Then, select the Group By option again and respond to its window as before.
You might use the Group By option in these different ways:
• An overlay of linear regression lines lets you compare slopes visually.
• An overlay of density ellipses can show clusters of points by levels of a grouping variable.
Related Information
• “Example of Group By Using Density Ellipses” on page 122
• “Example of Group By Using Regression Lines” on page 123