SPSS® 12.0 Command Syntax Reference

178 CASEPLOT
Figure 5 FORMAT=HILO
MARK Subcommand
Use MARK to indicate the onset of an intervention variable. Figure 6 shows a high-resolution
plot with a reference line indicating the year 1945.
• In high resolution, the onset date is indicated by a horizontal reference line. In low
resolution it is indicated by a tick mark on the left axis.
• The specification on MARK can be either a variable name or an onset date if the DATE_
variable exists.
• If a variable is named, the reference line indicates where the values of that variable
change.
• A date specification follows the same format as the DATE command, that is, a keyword
followed by a value. For example, the specification for June 1955 is Y 1955 M 6 (or Y 55
M 6 if only the last two digits of the year are used on DATE).
Figure 6 MARK=Y 1945
SPLIT Subcommand
SPLIT specifies how to plot data that have been divided into subgroups by a SPLIT FILE
command. The specification on SPLIT is either SCALE or UNIFORM.