SPSS® 12.0 Command Syntax Reference

NOT Logical Operator
Transformation Expressions 51
The NOT logical operator reverses the true/false outcome of the expression that immediately
follows.
• The NOT operator affects only the expression that immediately follows, unless a more
complex logical expression is enclosed in parentheses.
• The valid substitute for NOT varies from operating system to operating system. In
general, the tilde (~) is valid for ASCII systems, while ¬ (or the symbol over number 6
on the keyboard) is valid for IBM EBCDIC systems. See the SPSS Base User’s Guide
for your version of SPSS.
• NOT can be used to check whether a numeric variable has the value 0, 1, or any other
value. For example, all scratch variables are initialized to 0. Therefore, NOT (#ID) returns
false or missing when #ID has been assigned a value other than 0.
AND and OR Logical Operators
Two or more relations can be logically joined using the logical operators AND and OR.
Logical operators combine relations according to the following rules:
• The ampersand (&) symbol is a valid substitute for the logical operator AND. The vertical
bar ( | ) is a valid substitute for the logical operator OR.
• Only one logical operator can be used to combine two relations. However, multiple
relations can be combined into a complex logical expression.
• Regardless of the number of relations and logical operators used to build a logical
expression, the result is either true, false, or indeterminate because of missing values.
• Operators or expressions cannot be implied. For example, X EQ 1 OR 2 is illegal; you must
specify X EQ 1 OR X EQ 2.
• The ANY and RANGE functions can be used to simplify complex expressions.
AND Both relations must be true for the complex expression to be true.
OR If either relation is true, the complex expression is true.
Table 5 lists the outcome for AND and OR combinations.
Table 5 Outcome for AND and OR combinations
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
* Expressions where SPSS can evaluate the outcome with incomplete information. See “Missing
Values in Logical Expressions” below.