Count the occurrences of various sources of missing or invalid responses. The last three COUNT functions use CASE expressions to count the occurrences of the three notations for missing values. The "count me" character string gives the COUNT function a nonmissing value to count.

   count(case
            when &col=.n  then "count me"
            end) "Coded as NO ANSWER for &col",
   count(case
            when &col=.x  then "count me"
            end) "Coded as NOT VALID answers for &col",
   count(case
            when &col=.  then "count me"
            end) "Data Entry Errors for &col"
%mend;