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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: Difference Model |

Date |
Wed, 2 Nov 2011 08:21:20 +0000 |

That establishes that my comments on selecting observations may be pertinent. But on the other hand if you look at only those observations, you lose any dynamics and appear to assume instantaneous effects within the time resolution of the data. But you need economists working in this area to comment on which models might make sense -- and with annual data??? I am not an economist, so bail out at this point. Nick On Wed, Nov 2, 2011 at 8:00 AM, Vikram Finavker <vikramfinavker@gmail.com> wrote: > Hi, > > Sorry for not explaining why I want to use the model. Actually, I want > to examine the effects of hedging on risk measures when a firm either > starts hedging or stops hedging i.e. when h1 changes from 0 to 1 or > from 1 to 0. Hope this makes it clear now. > > Regards, > > Vikram Finavker > > On 1 Nov 2011, at 11:48 PM, Nick Cox <n.j.cox@durham.ac.uk> wrote: > >> I don't see how you think we can help. There is no context here and no explanation of why any model might make sense for whatever is your research problem. >> >> If you are saying that you want to select times at which -h1- differs from its previous value then >> >> ... if h1 != h1[_n-1] >> >> selects such observations. >> >> Nick >> n.j.cox@durham.ac.uk >> >> vikramfinavker >> >> I have a data like this... >> >> year firmid h1 x1 x2 x3 x4 x5 >> 1998 1 0 1 10 >> 1999 1 0 1 11 >> 2000 1 0 1 12 >> 2001 1 0 1 12 >> 2002 1 1 1 13 >> 2003 1 1 1 18 >> 2004 1 1 1 17 >> 2005 1 1 1 16 >> 2006 1 1 1 15 >> 2007 1 1 1 14 >> 1998 2 0 1 10 >> 1999 2 0 1 11 >> 2000 2 0 1 12 >> 2001 2 0 1 12 >> 2002 2 0 1 13 >> 2003 2 0 1 18 >> 2004 2 1 1 17 >> 2005 2 1 1 16 >> 2006 2 1 1 15 >> 2007 2 1 1 14 >> >> Now i want to run regression using following way; >> reg x3 h1 x2 >> >> but i want to use only those observations where variables "h1" changes to >> either "1" or "0". can i use first difference model.? Does it help me in >> this case? can i run regression like: >> >> reg x3 d.h1 x2 >> >> or do i have to run it like this >> >> reg d.x3 d.h1 d.x2 >> >> Please let me know if you can help. >> * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Difference Model***From:*vikramfinavker <vikramfinavker@gmail.com>

**st: RE: Difference Model***From:*Nick Cox <n.j.cox@durham.ac.uk>

**Re: st: RE: Difference Model***From:*Vikram Finavker <vikramfinavker@gmail.com>

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