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Re: st: Merging datasets
From
Oybek Rustamov <[email protected]>
To
"[email protected]" <[email protected]>
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 <[email protected]> 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
> <[email protected]> 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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