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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   Thu, 13 Oct 2011 07:35:58 +0100

Many thanks

Oybek

Sent from my iPhone

On 12 Oct 2011, at 22:49, Meredith Anderson <anderson.meredith.k@gmail.com> wrote:

> I think this should do it, as long as your data are unique by patient
> id, treatment date and test date:
> 
> 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): drop if _n<_N & _merge==3
> 
> This was in the second half of my previous email - I hope it answers
> your question. Thanks,
> 
> Meredith
> 
> On Tue, Oct 11, 2011 at 3:03 AM, Oybek Rustamov
> <oybek_rustamov@yahoo.co.uk> wrote:
>> 
>> 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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