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From |
"Carter Ivan Rees" <CRees1@uwyo.edu> |

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

Subject |
st: RE: Data manipulation: how to keep only consecutive obs in an unbalanced panel |

Date |
Mon, 11 Oct 2004 07:08:13 -0600 |

Roberto, There are duplicate commands already written for Stata, run help duplicates. The following link has also come in handy for me in the past if you are looking to count the recurrence of a particular individual across time. Your issue of consecutive years would require the code offered here to be tweaked a bit. http://www.stata.co.uk/support/faqs/data/dups.html Carter ************************************ Carter Rees, M.A. Email: crees1@uwyo.edu ************************************ -----Original Message----- From: Roberto [mailto:terrymondo@onetel.net.uk] Sent: Monday, October 11, 2004 6:35 AM To: statalist@hsphsun2.harvard.edu Subject: st: Data manipulation: how to keep only consecutive obs in an unbalanced panel Dear Statalist friends I am currently trying to run a GMM estimation using the xtabond2 command. I have an unbalanced panel so I would want to manipulate my dataset in a way that Stata only keeps the continuous observations for each firm For example consider these 3 firms code name year run maxrun _spell _seq _end n N 135540 A 1995 1 5 1 1 1 1 6 135540 A 1997 1 5 2 1 0 2 6 135540 A 1998 2 5 2 2 0 3 6 135540 A 1999 3 5 2 3 0 4 6 135540 A 2000 4 5 2 4 0 5 6 135540 A 2001 5 5 2 5 1 6 6 900327 B 1991 1 7 1 1 0 1 10 900327 B 1992 2 7 1 2 0 2 10 900327 B 1993 3 7 1 3 1 3 10 900327 B 1995 1 7 2 1 0 4 10 900327 B 1996 2 7 2 2 0 5 10 900327 B 1997 3 7 2 3 0 6 10 900327 B 1998 4 7 2 4 0 7 10 900327 B 1999 5 7 2 5 0 8 10 900327 B 2000 6 7 2 6 0 9 10 900327 B 2001 7 7 2 7 1 10 10 134982 C 1997 1 1 1 1 1 1 3 134982 C 1999 1 1 2 1 1 2 3 134982 C 2001 1 1 3 1 1 3 3 with the tsspell command I have been able to identify the maximum number of consecutive observations per firms. The problem is that if I write keep if maxrun>=5 stata only drops firm "C" whereas I would want it to drop all the non-consecutive observations in all panels so that the database would look like: code name year 135540 A 1997 135540 A 1998 135540 A 1999 135540 A 2000 135540 A 2001 900327 B 1995 900327 B 1996 900327 B 1997 900327 B 1998 900327 B 1999 900327 B 2000 900327 B 2001 Can anyone help? Thank you all for the kind attention. Best Regards Roberto Mura PhD candidate University of York * * 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/ * * 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/

**Follow-Ups**:**st: RE: Data manipulation: how to keep only consecutive obs in an unbalanced panel***From:*Roberto <terrymondo@onetel.net.uk>

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