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# st: RE: Panel data - Finding a match for an observation in one variable, from among some values of a different variable, in a previous time period

 From Adel Enpaya To "'statalist@hsphsun2.harvard.edu'" Subject st: RE: Panel data - Finding a match for an observation in one variable, from among some values of a different variable, in a previous time period Date Tue, 27 Nov 2012 11:17:49 +0000

```Dear
Can anyone show me how to run Tobit regression in stat 12
Thanks

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Rahul Ahluwalia
Sent: 27 November 2012 10:46
To: statalist@hsphsun2.harvard.edu
Subject: st: Panel data - Finding a match for an observation in one variable, from among some values of a different variable, in a previous time period

Dear Statalist
First of all, thank you. I've found many of the solutions posted here to be very helpful. I'll try and explain my current problem as best I can. I have some very inefficient and inelegant code that gets me what I need, but I would appreciate knowing the 'proper' way of doing this.

I have the following variables : year, id, comp_value, match_value, batch, test_flag. The data is in an unbalanced panel using year and id. test_flag indicates when an id enters the panel. I need to do the following - whenever test_flag == 1, I need to check that observation's match_value with the comp_value of all observations in the previous year that belong to the same batch and make note of the id. e.g

year id comp_value  match_value batch test_flag   match_id
1999  1   505	             76     9       0          .
1999  2   500	             89     8       0		.
1999  3   505	             98     8       0		.
2000  1   55	             10     9       0		.
2000  2   500	             40     9       0		.
2000  4   500	             505    8       1          .
2001  5   0			55	8	  1		.

The code I need would compare the match_value of id 4, year 2000, i.e 505, check it against the comp_value of all observations from year 1999 and the same batch(8) and change match_id to 3. The code would also check year 2001 and id 5 but would not cause any change in match_id. What would be really great is if another variable, say, match_count would tell me if there are multiple matches.

Regards
Rahul

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