Re: st: Data management problem

[n j cox <n.j.cox@durham.ac.uk>]

No suggestions from me, just a question.

How you do know that the examples refer to the same individual?
Are there identifier variable(s) too?

Nick
n.j.cox@durham.ac.uk

David W. Harless

I have two data sets containing dates of participation in two related 
programs, program 1
and program 2.  But the complication is that the program 1 data set 
lists dates if the
participant is enrolled in *either* program 1 or program 2.  Dates in 
the program 2 data
set indicate definite participation in program 2.

The best explanation is an example.  Here is program participation dates 
from the program
1 data set.  (Date variables have display format %dD_m_Y and I added the 
program variable
to make this explanation clearer):

          beg1        end1   program
     01 Jul 02   30 Nov 02         1
     01 Jul 03   30 Jun 05         1

And the same individual for the program 2 data set:

          beg2        end2   program
     01 Jul 02   30 Nov 02         2
     01 Oct 03   31 Dec 04         2
     01 May 05   31 May 05         2


I want to combine these records to obtain a data set that looks like:

           beg         end   program
     01 Jul 02   30 Nov 02         2
     01 Dec 02   30 Jun 03         0
     01 Jul 03   30 Sep 03         1
     01 Oct 03   31 Dec 04         2
     01 Jan 05   30 Apr 05         1
     01 May 05   31 May 05         2
     01 Jun 05   30 Jun 05         1

(where the 0 indicates the individual did not participate in either 
program during that
period).

There are, of course, many individuals with varying dates of 
participation in one or both
programs.  Any suggestions as to how one might solve this problem?

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/