Date: Fri, 30 Nov 2001 10:43:40 -0000
Reply-To: Nigel.Pain@SCOTLAND.GSI.GOV.UK
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Nigel Pain <Nigel.Pain@SCOTLAND.GSI.GOV.UK>
Subject: Re: First.Variable Question - Resolved
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A few comments on your code and an attempt to explain why the resolution
worked.
First, as a point of style, I always recommend that the BY statement
immediately follows the SET (or MERGE or UPDATE) statement. Syntactically it
doesn't matter because SAS deals with it at compilation, not execution, but
it makes the program clearer to us poor mortals. Likewise, I put most of the
other compilation-time statements (eg. *RETAIN*, LENGTH, FORMAT, INFORMAT,
ATTRIB, ARRAY, KEEP, DROP) immediately after the DATA statement unless there
is a good reason not to (can't think of any off-hand). It makes the program
easier for humans to interpret and can have the benefit of not overwriting
data if you accidentally leave the semicolon off the DATA statement (write
the simplest step possible and work out what happens if you do omit that
semicolon - hint: look for a dataset called WORK.SET!).
Second, the NOTSORTED option is unnecessary because you have sorted the BY
variables.
Third, on you subsetting IF statement, none of the parentheses are strictly
necessary as the only logical operator is AND. Once again, style only for
easy reading.
Fourth, the "payer in: ('Plan A')" condition is redundant in your second
step because you have already subsetted on that in the first step.
Last, when you combine all those conditions in a single IF statement using
the AND logical operator, then they all have to be true. Let's take a
simplified situation where you want IP=1 and first.DateOfService, and data
as follows:
IP DateOfService
1 1/1/01
2 1/1/01
3 1/1/01
2 2/1/01
1 2/1/01
1 2/1/01
In your original program, the first record would be selected (IP=1 and
first.DateOfService=1) and the second and third, correctly, would not (on
both counts). Now look at the fourth to sixth records. The fourth would not
be selected because IP=2 (even though first.DateOfService=1). However, the
fifth and sixth would also not be selected because, although IP=1,
first.DateOfService=0. When you use the corrected program, subsetting by IP
in the first step and by first.DateOfService in the second, after the first
step you have the following:
IP DateOfService
1 1/1/01
1 2/1/01
1 2/1/01
In the second step, the first two of these records fulfils the
first.DateOfService condition. BINGO!!
I hope this is helpful.
***************************************************
Nigel Pain
Scottish Executive Development Department
Business Support Unit
Victoria Quay
EDINBURGH
EH6 6QQ
UK
Tel +44 131 244 7237
Fax +44 7092 014235
Mailto:nigel.pain@scotland.gsi.gov.uk
Website: http:\\www.scotland.gov.uk
> -----Original Message-----
> From: Catherine Ward [mailto:CWard@ACCORDANT.NET]
> Sent: 29 November 2001 17:48
> Subject: Re: First.Variable Question - Resolved
>
>
> I still don't understand why the problem occurred, but the
> resolution was to
> break it into two distinct steps. I'd like to thank all who offered
> suggestions. The dialogue helped me to step back and
> realize I didn't need
> to do this all in one step. The code (again, less the myriad
> of fields
> defining my inclusion criteria) is below.
>
> Thanks again!
>
> Catherine Ward, RN, MSN/MBA
> Medical Economics Analyst
> Accordant Health Services
> cward@accordant.net
> (336) 315-3757
> Visit our patient communities at http://www.accordant.com or
> our corporate
> site at http://www.accordant.net
>
> --------------------------------------------------------------
> --------------
> --------------------------------------------------------------
> --------------
> --------------
> proc sort data = &OTLIB..StudyClaims;
> by payer MemberID DateOfService;
> run;
>
> data &OTLIB..preadmits ( keep = DateOfService ServCatI
> ServCatII ServCatIII
> MemberID payer disease admits IP);
> set &OTLIB..StudyClaims;
> if payer in: ('Plan A') then do;
> IP = ( ...< criteria from other fields inserted here> ...);
> by payer MemberID DateOfService;
> retain admits 1;
> if ( IP = 1 and ( ServCatI =: '007'and ServCatII ^=:'011'));
> output &OTLIB..admits;
> end;
> run;
>
> data &OTLIB..admits ;
> set &OTLIB..preadmits;
> if payer in: ('Plan A') and first.DateOfService;
> run;
> --------------------------------------------------------------
> --------------
> --------------------------------------------------------------
> --------------
> --------------
>
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