Boxplots of Z Scores

  1. To visually scan the z scores and find unusual values, from the menus choose:

    Graphs > Legacy > Boxplot...

  2. In the Boxplot dialog, elect Summaries of separate variables.
  3. Click Define.
    Figure 1. Boxplot dialog box
    Boxplot dialog box for defining a simple boxplot
  4. Select Zscore: Log-long distance through Zscore: Log-wireless as the variables the boxes represent.
  5. Click Options.
  6. In the Options dialog, select Exclude cases variable by variable.
  7. Click Continue.
  8. Click OK in the Define Simple Boxplot dialog box.
Figure 2. Boxplot of selected variables
Boxplot of five selected variables

Boxplots of the z scores show that customer 567 spent much more than the average customer on toll-free service last month. This should account for the larger skewness and kurtosis observed in Toll free last month.