Question

I would like to use proc sql in sas to identify if a case or record is missing some information. I have two datasets. One is a record of an entire data collection, that shows what forms have been collected during a visit. The second is a specification of what forms should be collected during a visit. I have tried many options including data steps and sql code using not in to no avail…

Example data is below

---

*****  dataset crf is a listing of all forms that have been filled out at each visit ;
*****  cid is an identifier for a study center  ;
*****  pid is an identifier for a participant  ;

data crf;
  input visit cid pid form ;
cards;
1 10 101 10
1 10 101 11
1 10 101 12
1 10 102 10
1 10 102 11
2 10 101 11
2 10 101 13
2 10 102 11
2 10 102 12
2 10 102 13
;
run;


*****  dataset crfrule is a listing of all forms that should be filled out at each visit  ;
*****  so, visit 1 needs to have forms 10, 11, and 12 filled out  ;
*****  likewise, visit 2 needs to have forms 11 - 14 filled out  ;

data crfrule;
  input visit form ;
cards;
1 10
1 11
1 12
2 11
2 12
2 13
2 14
;
run;


*****  We can see from the two tables that participant 101 has a complete set of records for visit 1 ;
*****  However, participant 102 is missing form 12 for visit 1 ;
*****  For visit 2, 101 is missing forms 12 and 14, whereas 102 is missing form 14  ;


*****  I want to be able to know which forms were **NOT**  filled out by each person at each visit (i.e., which forms are missing for each visit)  ;


*****  extracting unique cases from crf ;
proc sql;
  create table visit_rec as
    select distinct cid, pid, visit
      from crf;
quit;



*****  building the list of expected forms by visit number ;
proc sql;
  create table expected as 
    select  x.*,
            y.*

    from visit_rec as x right join crfrule as y
      on x.visit = y.visit

    order by visit, cid, pid, form;
quit;


*****  so now I have a list of which forms that **SHOULD** have been filled out by each person  ;

*****  now, I just need to know if they were filled out or not...  ;

---

The strategy I have been trying is to merge expected back onto the crf table with some indicator of which forms are missing for each visit.

Optimally, I would like to produce a table that would have: visit, cid, pid, missing_form

Any guidance is greatly appreciated.

Answer 1

You could use a left join and use the where clause to filter out the records with missing records in the right table.

 select 
  e.* 
 from
  expected e left join 
  crf c on
   e.visit = c.visit and 
   e.cid = c.cid and
   e.pid = c.pid and
   e.form = c.form
 where c.visit is missing
;