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Re: st: Loop year variable


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Loop year variable
Date   Sun, 21 Oct 2012 12:17:31 +0100

This should yield to a treatment in terms of spells in the sense of
-tsspell- (SSC) and of

SJ-7-2  dm0029  . . . . . . . . . . . . . . Speaking Stata: Identifying spells
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q2/07   SJ 7(2):249--265                                 (no commands)
        shows how to handle spells with complete control over
        spell specification

Look at -tsspell- first; it is self-contained. That is, your panels
are defined by country pairs (dyads) and the start of a spell is
defined by a match taking place (or a particular result; I don't
follow exactly what you want, e.g what about draws?). Then a variable
defined by -tsspell- gives you sequence in spell. You may need to
subtract 1.

I don't see that loops are needed.

Nick

On Sun, Oct 21, 2012 at 12:07 PM, emanuele mazzini
<madsoenistata@gmail.com> wrote:

> I am not a new Stata user, but I have to admit I still encounter some
> problems with writing loops. A loop may not be the solution to the
> issue I am going to describe, but I thought it is tough.
>
> I do have a dataset where I have country-pair trade observations for
> years 1950-2006 as well as another information, which is football
> match result for some dyads. I therefore need to generate a variable
> that indicates how many years are passed since the last won/lost of a
> country versus another. Suppose FT_A and FT_B are the final results
> for team A and B. I thought to generate a variable as follows:
>
> gen int date_won=year if FT_A>FT_B | FT_A<FT_B
>
> in order to get a variable that is = year for every observation I have
> information about, which reports the year of the won/loss. I then
> thought to generate another variable (let's say yrs_won) to tell me
> how many years have gone by as follows:
>
> gen int yrs_won=year-date_won
>
> Unfortunately, I do not get what I want: the only value yrs_won
> assumes is 0, but for all years from 1983 until 2006 I would like it
> to be 1, 2,3 and so on.
>
> At the beginning I didn't realize the problem, now it may be occur due
> to the fact that date_won = year only for the year in which the match
> was played. I guess I need to do something such as writing a loop to
> let it spread over all cells of such variable, but I don't really know
> how to make it. Does anyone of you has any suggestion?
>
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