Re: st: RE: RE: A Question on Selecting a Sample from a Panel Data Set

[Hong Nguyen <nguyen@scranton.edu>]

Hi Nick,

I have two years of derivative use data (2000 and 2001). I could select 
a sample of firms based on derivative use in either 2000 or 2001 (and 
spread that property to other observations for the same firms). How 
would I modify your previous commands to fit this situation?
Thanks!
Hong


Nick Cox wrote:
> Not quite. 
>
> -derivuse- is undefined, namely missing, for years not 2000. You need to
> spread that property to other observations for the same firms. 
>
> bysort firm (derivuse) : replace derivuse = derivuse[1] == 1 
>
> Nick 
> n.j.cox@durham.ac.uk 
>
> Martin Weiss
>
> If your dataset looks like this:
>
> ***********
> clear*
>
> set obs 19
> gen int year=_n+1986
>
> //10 firms
> expand 10
> bys year: gen byte firm =_n
> gen byte derivuse=runiform()>.25 if year==2000
> ***********
>
> you can simply condition on -if derivuse==1- in your analyses.
>
> Hong Nguyen
>
> I have a panel data set consisting of financial data for 423 firms over 
> a 19-year period.  For one of the years (2000) I have data on 
> derivatives use (use or non-use) for these 423 firms. I need to generate
> a sample of firms that used derivatives in 2000 and use it to run 
> regressions over the entire period 1987-2005. This is where I'm stuck.
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