RE: st: filling in existing ids and generating new ids for unique actors

[Erik Aadland <erikaadland@hotmail.com>]

In some of my cases, the observation for -actor- is rightfully missing.
Could this missing "value" for -actor- produce the error message?:
5 contradictions in 1079 by-groups
assertion is false
r(9);
Having consulted Manual [D] for the assert command, example 1 seems to suggest this.
Kind regards,
Erik.

----------------------------------------
> From: erikaadland@hotmail.com
> To: statalist@hsphsun2.harvard.edu
> Subject: RE: st: filling in existing ids and generating new ids for unique actors
> Date: Fri, 7 Sep 2012 14:37:37 +0000
>
> Having run the code:
> bysort actor (actor_id) : replace actor_id = actor_id[_n-1] if missing(actor_id)
> and followed up with the check:
> by actor : assert actor_id[1] == actor_id[_N]
>
> I got the following error message:
> 5 contradictions in 1079 by-groups
> assertion is false
> r(9);
> I tried to search for technique on how I can identify these 5 contradictions so that I can fix the problem, but could not find any.
> Any suggestions on how to proceed?
> Kind regards,
> Erik.
>
>
>
> ----------------------------------------
> > Date: Fri, 7 Sep 2012 14:12:01 +0100
> > Subject: Re: st: filling in existing ids and generating new ids for unique actors
> > From: njcoxstata@gmail.com
> > To: statalist@hsphsun2.harvard.edu
> >
> > Comments embedded below.
> >
> > Nick
> >
> > On Fri, Sep 7, 2012 at 1:03 PM, Erik Aadland <erikaadland@hotmail.com> wrote:
> > > Dear Statalist.
> > > I have an unbalanced panel dataset.
> > > The structure is as follows:
> > > year actor_id actor
> > > 2000 . Paul
> > > 2001 . Paul
> > > 2002 . Paul
> > > 2000 . Sarah
> > > 2001 1 Sarah
> > > 2002 1 Sarah
> > > 2000 . Simon
> > > 2001 2 Simon
> > > 2002 2 Simon
> > > I have 2 problems:
> > > 1. I want to fill in the missing existing actor_id for those actors that already have an actor_id in some years but not others.
> >
> > That's
> >
> > bysort actor (actor_id) : replace actor_id = actor_id[_n-1] if
> > missing(actor_id)
> >
> > But follow by a check:
> >
> > by actor : assert actor_id[1] == actor_id[_N]
> >
> > For the principles, see
> >
> > 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
> >
> > > 2. I want to generate a new unique actor_id for those actors that have no actor_id in the dataset. This actor_id needs to be different from those already existing for other actors in the dataset.
> > > The variable -actor- lists the unique name for each actor and this unique name could be used as a basis for assigning the actor_id.
> >
> > su actor_id, meanonly
> > local max = r(max)
> > egen new_actor_id = group(actor) if missing(actor_id)
> > replace actor_id = new_actor_id + `max' if missing(actor_id)
> >
> > What this does:
> >
> > 1. Find the largest actor_id in use. So, it will be safe to use higher numbers.
> >
> > 2. Use -egen-'s -group()- to generate new ids to those without them.
> > These will run 1, 2, 3, ..
> >
> > 3. New actor_id = new id + maximum for those without them.
> > *
> > * 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/
> *
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> * http://www.ats.ucla.edu/stat/stata/ 		 	   		  
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