Working with Missing Values

The following table shows how to represent each type of missing value in raw data so that SAS reads and stores the value appropriately.

You can set values to missing within your DATA step by using program statements such as this one:

if age<0 then
age=.;

This statement sets the stored value of AGE to a numeric missing value if AGE has a value less than 0.

The following example sets the stored value of NAME to a missing character value if NAME has a value of “none”:

if name="none" then name='';

Alternatively, if you want to set to a missing value for one or more variable values, you can use the CALL MISSING routine. For example:

call missing(sales, name);

This sets both variable values to a missing value.

You can use the N and NMISS functions to return the number of nonmissing and missing values, respectively, from a list of numeric arguments.

When you check for ordinary missing numeric values, you can use code that is similar to the following:

if numvar=. then do;

If your data contains special missing values, you can check for either an ordinary or special missing value with a statement that is similar to the following:

if numvar<=.z then do;

To check for a missing character value, you can use a statement that is similar to the following:

if charvar=' ' then do;

The MISSING function enables you to check for either a character or numeric missing value, as in:

if missing(var) then do;

In each case, SAS checks whether the value of the variable in the current observation satisfies the condition specified. If it does, SAS executes the DO group.