Date:         Wed, 23 Mar 2005 20:44:24 GMT
Reply-To:     LWn <Lars.WahlgrenRemove@THIS.STAT.LU.SE>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         LWn <Lars.WahlgrenRemove@THIS.STAT.LU.SE>
Organization: Telia Internet
Subject:      SV: Easy way to get a count of how many times a value shows up?
Comments: To: sas-l@uga.edu

Alex Pavluck <apavluck@gmail.com> skrev i
diskussionsgruppsmeddelandet:1111607149.896873.216190@z14g2000cwz.googlegrou
ps.com...
> Ok.  I am having a problem that is causing me to do a lot of coding and
> I thought that the group might find this interesting.  If you don't
> know how to do it IN SAS then don't send me a suggestion.  Thanks.
>
> I have a case/control dataset that I am using to do conditional
> logistic regression modeling.  The dataset contains a variable denoting
> the matched pair (matched_pairs) and will have a value twice in the
> dataset for each pair.  For example:
> OBS    CASE    CONTROL   MATCHED_PAIRS  ETC
> 1       0         1            1         ...
> 2       1         0            1         ...
> 3       0         1            2         ...
> 4       1         0            2         ...
>
> Now, I have removed unmatched pairs but the process is very cumbersome.
>  Can some suggest a way that I can get a count of MATCHED_PAIRS and
> remove those observations where the count of MATCHED_PAIRS is <2
> (indicating that the pair is missing).

Something like this perhaps

data new ;
  set old ;
  by matched_pairs ;
  if first.matched.pairs and last.matched_pairs then delete ;
  count + first.matched_pairs ;
run ;

hth / LWn