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| From | "Ariel Linden, DrPH" <ariel.linden@gmail.com> |
| To | <statalist@hsphsun2.harvard.edu> |
| Subject | st: generating a variable that requires comparing two dates |
| Date | Thu, 11 Apr 2013 15:16:50 -0400 |
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 ************************************* * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/