spss中使用syntax操作missing值
PROBLEM:
When using IF commands, if I try to assign a missing value to a numeric variable by using a period (".") as in the following incorrect command syntax,
IF (OLDVAR = 9) NEWVAR=. .
SPSS
sees the period as the command terminator, and the missing value
doesn't get assigned appropriately. Also, if I try to recode an
existing numeric missing value into something else using a period (".")
as in the following incorrect command syntax,
IF (OLDVAR = .) NEWVAR = 4.
that doesn't work either.
SOLUTION:
Numeric Variables
Apparently, SPSS doesn't use the period (".") as an actual numeric missing value, only for display (output) purposes.
To create a new numeric missing value, use "$sysmis" after the equal sign, as in this example:
IF (OLDVAR = 9) NEWVAR = $SYSMIS.
To use a numeric missing value in an evaluation expression, use the MISSING(arg) function, as in this example:
IF MISSING(OLDVAR) NEWVAR = 4.
Character (String/Alphanumeric) Variables
Missing values in string variables are handled in a more straightforward manner.
To create a new string missing value, use quotation marks (' ', or " ") after the equal sign, as in this example:
IF (OLDVAR = 'X') NEWVAR = " ".
To use a string missing value in an evaluation expression, use quotes similar to the above, as in this example:
IF (OLDVAR=' ') NEWVAR = "XYZ".
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