SPSS® 12.0 Command Syntax Reference

Commands 9
• Transformation commands (IF, COUNT, COMPUTE, etc.) that are used to create and
modify variables must precede commands that assign labels or missing values to those
variables, and they must also precede the procedures that use those variables.
• Generally, the logical outcome of command processing determines command order. For
example, a procedure that creates new variables in the working data file must precede a
procedure that uses those new variables.
• Some commands, such as REREAD and END CASE, can appear only in an input program
where the cases are created. Other commands, such as SELECT IF, can appear only in a
transformation program after cases have been created. Still other commands, such as
COMPUTE, can appear in an input or transformation program. For a discussion of these
program states and command order, see Appendix A.
In addition to observing the rules above, it is often important to distinguish between commands
that cause the data to be read and those that do not, particularly for large data sources
such as databases. Commands that cause the data to be read include all statistical and graphing
commands, all commands that result in creation of new files, AUTORECODE, EXECUTE,
and SORT.
Transformation commands that alter the dictionary of the working data file, such as
MISSING VALUES, and commands that do not affect the working data, such as SET, SHOW,
and DISPLAY, take effect as soon as they are encountered in the command sequence regardless
of conditional statements that precede them. Table 1 lists all transformation commands
that take effect immediately.
Table 1 Transformation commands that take effect immediately
ADD VALUE LABELS PRINT FORMATS
DOCUMENT SPLIT FILE
DROP DOCUMENTS STRING
FORMATS VALUE LABELS
LEAVE VARIABLE LABELS
MISSING VALUES VECTOR
N OF CASES WEIGHT
NUMERIC WRITE FORMATS
Since these transformations take effect regardless of the conditional statements that precede
them, they cannot be applied selectively to individual cases, as shown in the following example:
DO IF AGE>69.
MISSING VALUES INCOME EXPENSES (0).
ELSE.
COMPUTE PROFIT=INCOME-EXPENSES.
END IF.
LIST.
The MISSING VALUES command is in effect when COMPUTE is executed, even if the condition
defined on DO IF is false. To treat 0 income and expenses as missing only for those older