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Re: st: Simulating time series with if else condition


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Simulating time series with if else condition
Date   Tue, 21 Feb 2012 23:17:25 +0000

A separate issue is that

if fyear == 1971 {

}

else if fyear > 1971 ...

will always be interpreted as

if fyear[1] == 1971 {

}
else if fyear[1] >= 1971 ...

which is presumably not what is wanted. So the code not only can but
also should be rewritten. See also

FAQ     . . . . . . . . . . . . . . . . . . . . .  if command vs. if qualifier
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  J. Wernow
        6/00    I have an if command in my program that only seems
                to evaluate the first observation, what's going on?
                http://www.stata.com/support/faqs/lang/ifqualifier.html

Nick

On Tue, Feb 21, 2012 at 11:09 PM, Christopher Baum <kit.baum@bc.edu> wrote:
> <>
> Untested, but I think you can replace
>
>
> if fyear==1971{
>     by id: replace debtlevel_sim=actual_debtlevel
> /*start with actual debt-level in 1971*/
>     }
> else if fyear>1971 & (L.debtlevel_sim+debtissue_sim)<=0 {        /*in
> years following 1971: no negative debt-level*/
>     by id: replace debtlevel_sim=0
>     }
> else {
>     by id: replace debtlevel_sim=L.debtlevel_sim+debtissue_sim
>
>
> with one line:
>
>
> by id: replace debtlevel_sim = cond( fyear==1971, actual_debtlevel, max(0, L.debtlevel_sim+debtissue_sim ))
>

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