Using a DATA Step to Check for Invalid Values

A simple DATA _NULL_ step can also be used to produce a report on out-of-range values. The approach here is the same as the one described in the section of Chapter 1 that begins on page 6.

Program 2-6. Using a DATA _NULL_ Step to List Out-of-Range Data Values

DATA _NULL_;
   INFILE "C:CLEANINGPATIENTS.TXT" PAD;
   FILE PRINT; ***Send output to the Output window;
   TITLE "Listing of Patient Numbers and Invalid Data Values";
   ***Note: We will only input those variables of interest;
   INPUT @1  PATNO    $3.
         @15 HR        3.
         @18 SBP       3.
         @21 DBP       3.;
   ***Check HR;
   IF (HR LT 40 AND HR NE .) OR HR GT 100 THEN PUT PATNO= HR=;
   ***Check SBP;
   IF (SBP LT 80 AND SBP NE .) OR SBP GT 200 THEN PUT PATNO= SBP=;
   ***Check DBP;
   IF (DBP LT 60 AND DBP NE .) OR DBP GT 120 THEN PUT PATNO= DBP=;
RUN;

Here is the output from Program 2-6.

Listing of Patient Numbers and Invalid Data Values

PATNO=004  HR=101
PATNO=008  HR=210
PATNO=009  SBP=240
PATNO=009  DBP=180
PATNO=010  SBP=40
PATNO=011  SBP=300
PATNO=011  DBP=20
PATNO=014  HR=22
PATNO=017  HR=208
PATNO=321  HR=900
PATNO=321  SBP=400
PATNO=321  DBP=200
PATNO=020  HR=10
PATNO=020  SBP=20
PATNO=020  DBP=8
PATNO=023  HR=22
PATNO=023  SBP=34

Notice that a statement such as “IF HR LT 40” includes missing values because missing values are interpreted by SAS programs as the smallest possible value. Therefore, the following statement

IF HR LT 40 OR HR GT 100 THEN PUT PATNO= HR=;

will produce a listing that includes missing heart rates as well as out-of-range values (which may be what you want).