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RE: st: creating an unique household identification number


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: creating an unique household identification number
Date   Fri, 1 Sep 2006 20:02:49 +0100

No, I didn't mean that. That would be illegal. 

I meant what I said, -group()- with the -label- option. 

Note the convention of using - - to indicate literal 
Stata code within. Admittedly, the convention of describing 
-egen- functions in this way 

-egen, group()- 

includes a comma that you don't actually type. In 
your case the solution contemplated was 

egen newhhid = group(batch_nu hhid_nu), label

except that you confirmed my guess that you have too many 
observations for this to work. 

Type -help limits- and scroll to -label-. You can't have
3.5 million labels. Thus one of Friedrich's other suggestions
or -egen, concat()- should be nearer the mark. 

Nick 
n.j.cox@durham.ac.uk 

Simo Hansen
 
> Thanks Nick for your contribution. Indeed, I have a big data 
> set-3.5 million
> observations.
> When you suggested using label with egen group (), do you 
> mean to use this
> command in the following form?
> egen double newhhid=(batch_nu hhid_nu).

Nick Cox
 
> In addition, -egen, concat()- works either way, 
> and even with a combination of numeric and string 
> inputs. The result is always string. 
> 
> Incidentally, with -egen, group()- you would
> usually like to add the -label- option. However, 
> Simo's dataset might be really big, in which 
> case -egen, concat()- might offer the better choice. 
 
Friedrich Huebler
  
> > If both variables are numeric you can do this:
> > 
> > . gen long id1 =  Batch_nu*10 + hhid_nu
> > 
> > If both variables are strings you can do this:
> > 
> > . gen id2 = Batch_nu + hhid_nu
> > 
> > This command works with strings and numeric variables:
> > 
> > . egen id3 = group(Batch_nu hhid_nu)
 

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