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From |
Joe Canner <jcanner1@jhmi.edu> |

To |
"statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: Merge problem |

Date |
Fri, 4 Oct 2013 11:56:06 +0000 |

Erik, If there are a fixed, known number of periods per year, you can use -expand- in dataset (A). Suppose (as in your example) there are 4 periods (1,2,3,4): . expand 3 . bys year firm_id: gen period_id=_n However, if the number of periods depends on some information in dataset (B), that's a different story. If so, please provide more information on how the number of periods is to be determined. Regards, Joe Canner Johns Hopkins University School of Medicine ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] on behalf of Erik Aadland [erikaadland@hotmail.com] Sent: Friday, October 04, 2013 4:18 AM To: statalist@hsphsun2.harvard.edu Subject: st: Merge problem Dear Statalist. I have two datasets. One dataset (A) contains the variables "year" and "firm_id". A firm observation ("firm_id") occurs only once in a given "year". The other dataset (B) contains the variables "year", "period_id" and "firm_id". There are many periods within a given year, and firm observations ("firm_id") are nested within periods. So a given firm ("firm_id") may occur several times in a given year. The firms in (A) are not the same firms as in (B). The structure of (A) and (B) are as follows. (A): year firm_id 2003 1 2003 2 2003 3 2003 4 2004 1 2004 2 2004 5 2004 6 (B): year period_id firm_id 2003 1 11 2003 1 12 2003 2 13 2003 2 14 2003 2 11 2004 3 11 2004 3 12 2004 3 15 2004 4 16 2004 4 17 I want to merge the firms in (A) into (B) such that the firms in (A) in a given year occur in all periods for the corresponding year in (B). The problem is that I don't have "period_id" for my firm observations in (A). Is there a smart way to handle this problem? I use Stata 12. Any input on this would be much appreciated. Sincerely, Erik * * 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/ * * 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/

**Follow-Ups**:**RE: st: RE: Merge problem***From:*Erik Aadland <erikaadland@hotmail.com>

**References**:**st: Merge problem***From:*Erik Aadland <erikaadland@hotmail.com>

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