Date: Tue, 19 Dec 2006 02:36:37 -0800
Reply-To: SK <skauchali@GMAIL.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: SK <skauchali@GMAIL.COM>
Organization: http://groups.google.com
Subject: Algorithm to create new var based on knowledge of date and other
var
Content-Type: text/plain; charset="iso-8859-1"
Hi There (sorry this is a long message; I have tried to keep it clear;
let me know if there is further information you require)
Let me start by admitting that I am not an expert at repeated
observation in SAS, and I think I should spend time learning it before
I resort to asking more question here. I have Cody's book (long. data
and SAS), which seems to help. But I thought I would post to fast track
my objectives. Here is the problem: data table is as
Childid date result
100611 19FEB2002 No
100611 11JUN2002 No
100611 08JUL2003 No
100611 08JUL2004 No
100651 09APR2002 No
100651 15OCT2003 No
101061 30APR2002 No
101061 27AUG2002 No
101061 12NOV2002 No
101121 16MAY2002 No
101121 16JUL2002 Yes
101161 22JAN2002 No
101161 21MAY2002 No
101271 11DEC2001 No
101271 02APR2002 No
101271 22APR2003 No
101361 02APR2002 No
101361 25JUL2002 No
101361 19MAY2003 No
101371 29JAN2002 No
101371 21MAY2002 No
101371 01JUL2003 No
101391 26MAR2002 No
101391 23JUL2002 No
101391 19MAY2003 Yes
101561 26MAR2002 No
101611 02JAN2002 No
101611 29JAN2002 No
101651 26MAR2002 No
101651 24JUL2002 No
101651 01SEP2003 No
101691 02JUL2002 No
101691 13AUG2002 Yes
101691 01OCT2002 Yes
101691 05NOV2002 Yes
101691 26AUG2003 Yes
101691 30SEP2003 Yes
101711 21MAY2002 Yes
101711 02JUL2002 Yes
101711 03SEP2002 Yes
101711 14JUL2003 Yes
307511 30NOV2004 Yes
307601 26APR2005 No
As you can see, a child has had either just one measurement or multiple
measurements (result) at different dates. The RESULT is a test result.
If the child test YES at a date, then the test is positive
(TEST=positive). If RESULT is NO on all dates then the TEST=negative.
What is important is the date when the RESULT was YES.
I would like to program in SAS an algorithm that will identify a child
who is test positive and date when it was positive. So for example,
these 2 children
307511 30NOV2004 Yes
307601 26APR2005 No
only had one test done. If child only has one obs then TEST=RESULT and
DATETEST=DATE- in these 2 cases the data will look like this:
Childid date result test datetest
307511 30NOV2004 Yes Yes 30NOV2004
307601 26APR2005 No No 26APR2005
In cases where the child had more than one obs, it is a bit tricky for
me. If any of the dates had a RESULT=YES, then TEST=YES and DATETEST=
<date when first time when RESULT=YES>; Take this subject as an
example:
Childid date result test
datetest
101691 02JUL2002 No
101691 13AUG2002 Yes Yes 13AUG2002
101691 01OCT2002 Yes
101691 05NOV2002 Yes
101691 26AUG2003 Yes
101691 30SEP2003 Yes
If all of the results on all dates are NO, then the test is also NO;
and the last date of result is recorded; thus:
Childid date result test
datetest
101361 02APR2002 No
101361 25JUL2002 No
101361 19MAY2003 No No 19MAY2003
If I look at this, it would seem that subjects with only one
measurement are a special case of multiple obs (where the wave is equal
to one).
I would like to then take the obs that have a test and datetest var
populated as above from this dataset and merge it with the flat data
set with all children in it. Can someone help me with the code and
direction.
Thanks
SK
