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From |
Roberto <terrymondo@onetel.net.uk> |

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 15:29:09 +0100 |

Dear Carter

thank you very much for your kind reply

I am actually aware of the command you suggested but I am not sure how I could use it.

I am sorry maybe I was not as clear as I wished before.

Say for example that for a firm in my unbalanced panel I have observations for the years: 1991,1992,1997,1998,1999,2000,2001.

So this firm has N=7 and maxrun=5

What I would like to do is to find a command to drop 1991 and 1992 and to keep only the 5 consecutive observations.

Kind regards

Roberto Mura

PhD candidate

University of York

At 14:08 11/10/2004, you wrote:

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/

* * 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/

**References**:**st: RE: Data manipulation: how to keep only consecutive obs in an unbalanced panel***From:*"Carter Ivan Rees" <CRees1@uwyo.edu>

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