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Re: st: Merging datasets


From   Oybek Rustamov <oybek_rustamov@yahoo.co.uk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Merging datasets
Date   Tue, 11 Oct 2011 11:03:00 +0100

Dear Meridith

Many thanks for your help. 

More more question- how can I keep closest blood result if patient had more than one blood test before the treatment date? 

Regards

Oybek

Sent from my iPhone

On 10 Oct 2011, at 19:33, Meredith Anderson <anderson.meredith.k@gmail.com> wrote:

> I would use joinby, and then drop the records that you don't need.
> 
> use treatment.dta
> joinby patientid using bloodresults.dta, unmatched(both)
> 
> ("unmatched(both)" keeps unmatched patient IDs from both datasets. The
> default - "unmatched(none)" - is to drop observations connected with a
> patient ID that is only in one dataset. The unmatched option will
> accept "both", "master", "using" or "none")
> 
> To get rid of blood tests after the treatment date:
> drop if treatmentdate<testdate & _merge==3
> 
> To keep the most recent test before the treatment date:
> bysort patientid treatmentdate testdate: assert _N==1
> bysort patientid treatmentdate (testdate): drop if _n<_N & _merge==3
> 
> If I'm understanding what you need correctly, I think this will do it.
> 
> On Sun, Oct 9, 2011 at 1:30 PM, Oybek Rustamov
> <oybek_rustamov@yahoo.co.uk> wrote:
>> 
>> Dear All
>> 
>> Could you help me with merging my two datasets. In my datasets some patients had more than two treatment cycles and number of blood tests. I  need to merge blood results that is closest to treatment date and before the treatment date.
>> 
>> This is example of my datasets.
>> 
>> 1) Treatment dataset
>> 
>> Patient ID    Treatment date
>> 
>> A.                 01/01/09
>> A.                 05/07/10
>> 
>> B.                  10/10/10
>> B.                  12/10/11
>> 
>> 
>> 2) Blood results dataset
>> 
>> Patient ID       Test date
>> 
>> A.                  12/12/2008
>> A.                  10/09/2008
>> A.                   01/01/2011
>> 
>> 
>> B.               10/09/2009
>> B.                03/09/2010
>> B.                04/05/2011
>> 
>> Many thanks
>> 
>> Oybek
>> 
>> 
>> 
>> Sent from my iPhone
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