When is a result of a computation missing?

Missing values can return a computation result that is system-missing under a variety of conditions. For a comprehensive discussion of missing values, see Missing values.

There are also conditions under which missing values in computations will not return a missing value, including:

• A computation that includes multiplication by zero will return a result of zero, regardless of the presence of missing values.
• A computation that involves division where the numerator resolves to zero will return a result of zero, regardless of the presence of missing values in the denominator.
• If the result of the computation is a string, the result will usually not be missing, even if the computation includes missing values. (If the result is a blank string and a blank string is defined as user-missing for the result variable, then the result will be user-missing.)