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| From | Rahul Ahluwalia <Rahul_Ahluwalia@isb.edu> |
| To | "statalist@hsphsun2.harvard.edu" <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 |
| Date | Tue, 27 Nov 2012 16:15:46 +0530 |
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 * * 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/