Date:         Thu, 19 Mar 2009 12:04:43 -0700
Reply-To:     "Terjeson, Mark" <Mterjeson@RUSSELL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Terjeson, Mark" <Mterjeson@RUSSELL.COM>
Subject:      Re: Calculate time interval
Comments: To: Sid <sjain@AVEOPHARMA.COM>
In-Reply-To:  A<200903191841.n2JGa3pp023800@malibu.cc.uga.edu>
Content-Type: text/plain; charset="US-ASCII"

Hi Sid,

Here is one approach using BY processing
which set FIRST. and LAST. flags to use:




data sample;
    input subjid visit visitdt date9. status $;
    format visitdt date9.;
cards;
1 1 31dec2008 CR
1 2 14jan2009 PR
1 3 22jan2009 SD
1 4 07feb2009 PD
;
run;

    * insure BY ordering ;
proc sort data=sample;
    BY subjid visit;
run;

    * use FIRST. processsing ;
data result(drop=prev_date start_date);
    set sample;
    BY subjid visit;
    prev_date = lag(visitdt); * date from prior record ;

        * reset new var for each subj ;
    if first.subjid then start_date = .;

        * save PR date if found ;
    if status eq 'PR' then start_date = visitdt;

        * use PR date if found, else use last date ;
    if start_date eq . then
        do;
            if not first.subjid then start_date = prev_date;
            if last.subjid then diff = visitdt - start_date;
        end;
run;



Hope this is helpful.


Mark Terjeson
Senior Programmer Analyst
Investment Management & Research
Russell Investments
253-439-2367


Russell
Global Leaders in Multi-Manager Investing







-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Sid
Sent: Thursday, March 19, 2009 11:42 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Calculate time interval

I have a dataset like below:

subjid visit visitdt status
1        1    --        CR
1        2    ---       PR
1        3    ---       SD
1        4    ---       PD

I need to calculate the difference in time - from when status is PR  to
PD.
 PD is always the last visit, PR can occur in any of the visits. If PD
is
not present I need to replace PD with the last visit's date.


Thanks,
Sid