Using Conditional Expressions

You can use conditional expressions (also called logical expressions) to apply transformations to selected subsets of cases. A conditional expression returns a value of true, false, or missing for each case. If the result of a conditional expression is true, the transformation is applied to that case. If the result is false or missing, the transformation is not applied to the case.

To specify a conditional expression:

1. Click If in the Compute Variable dialog box. This opens the If Cases dialog box.
2. Select Include if case satisfies condition.
3. Enter the conditional expression.

Most conditional expressions contain at least one relational operator, as in:

age>=21

or

income*3<100

In the first example, only cases with a value of 21 or greater for Age [age] are selected. In the second example, Household income in thousands [income] multiplied by 3 must be less than 100 for a case to be selected.

You can also link two or more conditional expressions using logical operators, as in:

age>=21 | ed>=4

or

income*3<100 & ed=5

In the first example, cases that meet either the Age [age] condition or the Level of education [ed] condition are selected. In the second example, both the Household income in thousands [income] and Level of education [ed] conditions must be met for a case to be selected.

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