Modeling and Multivariate Methods - SAS

450 Correlations and Multivariate Techniques Chapter 17
Multivariate Platform Options
Figure 17.3 Clusters of Correlations
By default, a 95% bivariate normal density ellipse is shown in each scatterplot. Assuming the variables are
bivariate normally distributed, this ellipse encloses approximately 95% of the points. The narrowness of the
ellipse shows the correlation of the variables. If the ellipse is fairly round and is not diagonally oriented, the
variables are uncorrelated. If the ellipse is narrow and diagonally oriented, the variables are correlated.
Working with the Scatterplot Matrix
Re-sizing any cell resizes all the cells.
Drag a label cell to another label cell to reorder the matrix.
When you look for patterns in the scatterplot matrix, you can see the variables cluster into groups based on
their correlations. Figure 17.3 shows two clusters of correlations: the first two variables (top, left), and the
next four (bottom, right).
Options for Scatterplot Matrix
The red triangle menu for the Scatterplot Matrix lets you tailor the matrix with color and density ellipses
and by setting the α-level.
Table 17.2 Options for the Scatterplot Matrix
Show Points
Density Ellipses
Shows or hides the points in the scatterplots.
Shows or hides the 95% density ellipses in the scatterplots. Use the Ellipse
α menu to change the α-level.