st: creating loops to drop observations

[Kit Baum <baum@bc.edu>]

But why drop observations? Stata's if qualifier is perfectly capable  
of excluding them...

use dataset, clear
forval x=1/N {
	regress y x if code ~=  "country`x'"
}

That will run much faster for a sizable dataset since it does not  
keep reading the data over and over.
Furthermore if you are going to save any results of this cross- 
country estimation you do not want to keep changing the dataset.

Kit Baum, Boston College Economics
http://ideas.repec.org/e/pba1.html


On Apr 3, 2006, at 2:33 AM, statalist-digest wrote:


> Although in this example forval may be more appropriate...
>
> > > use dataset.dta, clear
> > > drop if code=="country1"
> > > regress y x
> > >
> > > use dataset.dta, clear
> > > drop if code=="country2"
> > > regress y x
> Assuming that code is always countryN then you could...
>
> forval x = 1/N{
>    use dataset, clear
>    drop if(code == "country`x'")
>    regress y x
> }
>
> You would substitute N in the above for the maximum country number.
>
> If however you actually have named countries such as "Australia",
> "United States", "Germany", "Nepal", "United Kingdom", "France" etc.
> then you would have to use foreach....
>
> foreach x in Australia "United States" France Germany "United  
> Kingdom" Nepal{
>    use dataset, clear
>    drop if(code == "`x'")
>    regress y x
> }
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