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SV: st: Deleting entire panel id/group if condition is true for first year


From   Andreas Dall Frøseth <Andreas.Froseth@stud.nhh.no>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   SV: st: Deleting entire panel id/group if condition is true for first year
Date   Wed, 1 May 2013 14:14:31 +0000

Maybe I'm applying it wrong, but this does not seem to do that I want. I may have described it a bit to badly.

So, here's an example.
At this point my set is containing all companies with a run equal to or above 6 years. I identify these by using -tsspell- (SSC), and then "egen length = max(_seq), by(orgnr _spell)" (orgnr is the identifyer), and drop the unwanted companies by "drop if length<6"
However, I also wish to drop entire panel groups (all six years for a company) if the variable "category" has a missing value the first year in the six year run. Leaving me with companies with runs equal to and above 7 years, in addition to companies with 6 year runs which have a value listed in the variable "category" the first year.

I hope this was a better explanation. Pardon me in advance if the only reason that your previous code doesn't work is due to my incompetence...

-Andreas
________________________________________
Fra: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] p&#229; vegne av Nick Cox [njcoxstata@gmail.com]
Sendt: 1. mai 2013 15:34
Til: statalist@hsphsun2.harvard.edu
Emne: Re: st: Deleting entire panel id/group if condition is true for first year

Stata makes this kind of change extremely easy.

bysort id (whatever) : keep if !missing(whatever[_N]) & _N >= 6

-sort-ing within panels means that any missings are sorted to last.

This is covered in any tutorial on -by:-.

Nick
njcoxstata@gmail.com

On 1 May 2013 14:14, Andreas Dall Frøseth <Andreas.Froseth@stud.nhh.no> wrote:
>
> Is it possible to delete a entire panel id/group from the set if a certain condition is true for the first year?
> I'm trying to keep certain spells in my dataset, and by using the -tsspell- (SSC) I have managed to keep panel variables with runs equal or above 7 years. But, I also wish to keep panel groups with 6 year runs IF the value in the variable "category" is nonmissing for the first year (or actually every year).

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