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Re: st: generating a variable that requires comparing two dates
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: generating a variable that requires comparing two dates
Date
Fri, 12 Apr 2013 01:33:52 +0100
One technique that can be useful with paired dates is to -expand 2-.
See http://www.stata-journal.com/article.html?article=dm0068
Nick
[email protected]
On 11 April 2013 20:16, Ariel Linden, DrPH <[email protected]> wrote:
> Hi fellow listers,
>
> This may be an easy task, but I am not getting it right...
>
> I would like to generate a new variable ( by ID) that will equal 1 if there
> was an alert (triggered on the surveydate, when that surveydate was the same
> as the admitdate. The obvious problem is that the dates are not always
> aligned so a straight "bys ID: gen test if surveydate==admitdate & alert==1"
> will not always work.
>
> In the data below, the code would need to "see" that the admitdate of
> 4/6/2011 has a corresponding surveydate a few lines down where the alert==1.
> Similarly, the next admitdate is 4/20/2011, so it would need to lookup the
> corresponding surveydate and verify that alert==1.
>
> I would then like to run this code again (generating a new variable) where
> we'd look to see if there was an alert on the surveydate the day before the
> admitdate (ie., surveydate = admitdate - 1)
>
> Thanks in advance!
>
> Ariel
>
> **** example data****
>
> ID surveydate alert admitdate
> 1 4/2/2011 1 4/6/2011
> 1 4/3/2011 1 4/20/2011
> 1 4/4/2011 0 4/20/2011
> 1 4/5/2011 0 4/20/2011
> 1 4/6/2011 1 4/20/2011
> 1 4/7/2011 0 4/20/2011
> 1 4/8/2011 0 4/20/2011
> 1 4/9/2011 0 4/20/2011
> 1 4/10/2011 0 4/20/2011
> 1 4/11/2011 0 4/20/2011
> 1 4/12/2011 0 4/20/2011
> 1 4/13/2011 0 4/20/2011
> 1 4/14/2011 0 4/20/2011
> 1 4/15/2011 0 4/20/2011
> 1 4/16/2011 0 4/20/2011
> 1 4/17/2011 0 4/20/2011
> 1 4/18/2011 0 4/20/2011
> 1 4/19/2011 0 4/20/2011
> 1 4/20/2011 1 4/20/2011
> 1 4/21/2011 0 4/20/2011
> *************************************
>
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