SPSS® 12.0 Command Syntax Reference

Flow of Control
DO IF 495
• If the logical expression on DO IF is true, the commands immediately following DO IF are
executed up to the next ELSE IF, ELSE, or END IF command. Control then passes to the
first statement following END IF.
• If the expression on DO IF is false, control passes to the following ELSE IF command.
Multiple ELSE IF commands are evaluated in the order in which they are specified until
the logical expression on one of them is true. Commands following that ELSE IF
command are executed up to the ELSE or END IF command, and control passes to the first
statement following END IF.
• If none of the expressions are true on the DO IF or any of the ELSE IF commands, the
commands following ELSE are executed and control passes out of the structure. If there
is no ELSE command, a case goes through the entire structure with no change.
• Missing values returned by the logical expression on DO IF or on any ELSE IF cause
control to pass to the END IF command at that point.
Missing Values and Logical Operators
Example
When two or more relations are joined by logical operators AND and OR, the program
always returns missing if all of the relations in the expression are missing. However, if any
one of the relations can be determined, the program tries to return true or false according
to the logical outcomes shown in Table 1. The asterisk indicates situations where the
program can evaluate the outcome with incomplete information.
Table 1 Logical outcome
Expression Outcome Expression Outcome
true AND true = true true OR true = true
true AND false = false true OR false = true
false AND false = false false OR false = false
true AND missing = missing true OR missing = true*
missing AND missing = missing missing OR missing = missing
false AND missing = false* false OR missing = missing
DO IF (YRHIRED LT 87).
RECODE RACE(1=5)(2=4)(4=2)(5=1).
END IF.
• The RECODE command recodes RACE for those individuals hired before 1987 (YRHIRED
is less than 87). The RACE variable is not recoded for individuals hired in 1987 or later.
• The RECODE command is skipped for any case with a missing value for YRHIRED.