Re: st: RE: testing -duplicates tag-

[Michael McCulloch <mm@pinest.org>]

Thanks, Martin. Very helpful.

> Well, as -help duplicates- shows, a -varlist- is allowed with all of 
> the fice commands. If you had the *OR* operator, this would be 
> pointless. -duplicates tag- watches out for unique combinations of 
> the variables in your -varlist- and then tags with the number of 
> other observations sharing this unique combination.
>
> sysuse auto, clear
> duplicates tag head mpg, gen(dup)
> duplicates report headroom mpg
> ta dup
>
> duplicates tag head mpg tru, gen(dup1)
> duplicates report headroom mpg tru
> ta dup1
>
>
> HTH
> Martin
>
> Quoting Michael McCulloch <mm@pinest.org>:
>
>
> > Thanks Martin. Am I correct in understanding that, in this revised
> > example immediately below, the command:
> >
> > 	. duplicates tag headroom trunk, generate(dup)
> >
> > would tag as dup>0 all sets of observations for which there are  
> > duplicates of:
> > 	headroom *AND* trunk
> > and not just those for which there are duplicates of:
> > 	headroom *OR* trunk
> > ?
> > It looks that way on visual inspection of this example's output, but I
> > want to make sure before applying it to my much larger dataset.
> >
> >
> > clear
> > sysuse auto
> > list foreign headroom trunk
> > duplicates tag headroom trunk, generate(dup)
> > sort headroom trunk
> > list foreign headroom trunk dup if dup>0, clean
> >
> > Michael
> >
> >
> >
> > > Well, the question is not much clearer now, at least to me. I  
> > > suspect you want something like
> > >
> > > count if duptag > 0
> > >
> > > after your commands. Just replace duptag with the tag used by 
> > > Stata  and be aware that two observations sharing the same 
> > > covariate  
> > > pattern would each be counted twice (58 and 59 would both count  
> > > under this rule). If that is not what you want, clarify!
> > >
> > >
> > > HTH
> > > Martin
> > >
> > > Quoting Michael McCulloch <mm@pinest.org>:
> > >
> > >
> > > > Apologies, I wasn't clear in my question. What I want to do is find
> > > > records for which *both* trunk and headroom are duplicates. So
> > > > following the command suggested by Martin and Nick, I get:
> > > >
> > > >
> > > > . list foreign headroom trunk if trunk==8, clean
> > > >
> > > >        foreign   headroom   trunk  20.   Domestic        2.0       8
> > > > 45.   Domestic        1.5       8  57.    Foreign        2.0       8
> > > > 58.    Foreign        2.5       8  59.    Foreign        2.5       8
> > > > Note that:
> > > > 	observations 20 and 57 both have headroom==2.0, trunk==8
> > > > 	observations 58 and 59 both have headroom==2.5, trunk==8
> > > >
> > > > Since I'm developing this command for use in a large dataset, how would
> > > > I follow up -duplicates tag- to identify those unique sets of records,
> > > > where two variables are duplicates simultaneously, without having to
> > > > search manually?
> > > >
> > > > > I cannot see your point. Stata does tag these observations with  
> > > > > tag 1. Just
> > > > > -list- after -duplicates tag-.
> > > > >
> > > > > **********
> > > > > clear
> > > > > sysuse auto
> > > > > list foreign headroom trunk if trunk==8
> > > > > duplicates tag headroom trunk, generate(dup_admission_id)
> > > > > *Let`s see...
> > > > > list dup_* foreign headroom trunk if trunk==8
> > > > > **********
> > > > >
> > > > > HTH
> > > > > Martin
> > > > >
> > > > > -----Original Message-----
> > > > > From: owner-statalist@hsphsun2.harvard.edu
> > > > > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of  
> > > > > Michael McCulloch
> > > > > Sent: Wednesday, September 03, 2008 6:29 PM
> > > > > To: Statalist
> > > > > Subject: st: testing -duplicates tag-
> > > > >
> > > > > Hello,
> > > > > I'm testing -duplicates tag-, and puzzled as to why it won't show the
> > > > > two observations where headroom==2.0 and trunk==8.
> > > > >
> > > > > clear
> > > > > sysuse auto
> > > > > list foreign headroom trunk if trunk==8
> > > > > duplicates tag headroom trunk, generate(dup_admission_id)
> > > > >
> > > > > --
> > > > >
> > > > > Best wishes,
> > > > > Michael McCulloch
> > > > >
> > > > >
> > > > >
> > > > > Pine Street Foundation
> > > > > 124 Pine St., San Anselmo, CA 94960-2674
> > > > > Tel:	(415) 407-1357
> > > > > Fax:	(415) 485-1065
> > > > > mcculloch@pinestreetfoundation.org
> > > > > www.pinestreetfoundation.org
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