RE: st: RE: Unbalancing a panel data set with country pairs

[Matei Frunzetti <matei.frunzetti@student.uni-tuebingen.de>]

Zitat von Nick Cox <n.j.cox@durham.ac.uk>:

> <sacrifice>
>
> . search identifier
>
> points you to useful information. In this case,
>
> egen idnew = group(id1 id2), label
>
> is one of the easiest solutions. There is also a miniature review of  
> possibilities at
> SJ-7-4  dm0034  . . . Stata tip 52: Generating composite categorical  
> variables
>         . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   
> N. J. Cox
>         Q4/07   SJ 7(4):582--583                                 (no  
> commands)
>         tip on how to generate categorical variables using
>         tostring and egen, group()
>
> but the help to -egen- -- which I did refer you to earlier --  
> contains enough to solve this problem.
> Nick
> n.j.cox@durham.ac.uk
>
> Matei Frunzetti
>
> Thank you for your timely answer and excuse me for not being clear
> enough: my main problem is that the country pairs have a single id for
> each country, so i need to introduce a new id with its values being
> unique identifiers for the respective country pairs such that i can
> use by etc.
>
> ex:
> id1   id2    idnew  var1 ...
>
> cty1  cty2   pair1  234
> cty2  cty1   pair2  456
>
> I am aware that this must seem pretty banal but i simply cannot find a
> thread or help that would adress this problem, I probably just don't
> know where to look.
>
> Zitat von Nick Cox <n.j.cox@durham.ac.uk>:
>
> > I assume that "country pair" defines a panel identifier.
> >
> > Look at the help for -egen-, which gives you one way to start.
> >
> > In terms of missings,
> >
> > egen missing_in_obs = rowmiss(varlist)
> > egen missing_in_panel = total(missing_in_obs), by(panelid)
> > drop if missing_in_panel
> >
> > In terms of not enough years, you don't quite say what the time
> > resolution of your data is. But assuming you have yearly
> > observations then
> >
> > bysort panelid : drop if _N < 17
> >
> > drops the short panels. If it's half-years, quarters, months, etc.
> > adjust as needed.
> >
> > You need to plug in your own <varlist> and <panelid>.
> >
> > The big concept you appear to be missing is that of working -by:-.
> > There is a tutorial at
> >
> > SJ-2-1  pr0004  . . . . . . . . . . Speaking Stata:  How to move
> > step by: step
> >         . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
> > N. J. Cox
> >         Q1/02   SJ 2(1):86--102                                  (no
> > commands)
> >         explains the use of the by varlist : construct to tackle
> >         a variety of problems with group structure, ranging from
> >         simple calculations for each of several groups to more
> >         advanced manipulations that use the built-in _n and _N
> >
> > Nick
> > n.j.cox@durham.ac.uk
> >
> > Matei Frunzetti
> >
> > I 'm working on a panel data set over 17 years. It's fairly unbalanced
> > und i need to drop all observations for country pairs that either lack
> > full length (as in years) or have missings in one of the independant
> > variables. The problem is that i have to delete all observations of
> > these country pairs for all years if only one or more variables have a
> > missing or if it is one or more years short. I ran into a dead end
> > trying to figure out how to imply the rest of the observations of a
> > "faulty" country pair into the drop command.
> *
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