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Re: st: RE: not uniquely identified observ in small panel


From   Joana Quina <[email protected]>
To   [email protected]
Subject   Re: st: RE: not uniquely identified observ in small panel
Date   Tue, 5 Jul 2005 21:42:53 +0100

Thanks for replying. I am sorry for the mix up - I was using "width"
with "xtdes" and not with "duplicates".

Here is what I typed and the output:
 
. duplicates report

Duplicates in terms of all variables

--------------------------------------
   copies | observations       surplus
----------+---------------------------
        1 |          128             0
--------------------------------------

. duplicates list

Duplicates in terms of all variables

(0 observations are duplicates)

. iis id

. tis year

. xtdes

      id:  1, 2, ..., 32                                     n =         32
    year:  1, 2, ..., 4                                      T =          4
           Delta(year) = 1; (4-1)+1 = 4
           (id*year does not uniquely identify observations)

Distribution of T_i:   min      5%     25%       50%       75%     95%     max
                         2       4       4         4         4       5       5

     Freq.  Percent    Cum. |  Pattern
 ---------------------------+---------
       29     90.63   90.63 |  1111
        1      3.13   93.75 |  1..1
        1      3.13   96.88 |  1121
        1      3.13  100.00 |  1211
 ---------------------------+---------
       32    100.00         |  XXXX

. xtdes , width(200)
option width() not allowed
r(198);



Thank you so much for your help!

Joana

On 05/07/05, Nick Cox <[email protected]> wrote:
> I am interested in your assertion that -duplicates-
> produces an incorrect result. But to say anything
> about it would require a sight of exactly what you
> typed and exactly what results you got, and/or a copy of the
> data, which you might care to send to me privately.
> 
> I wasn't aware that -duplicates- had a -width()- option.
> 
> Nick
> [email protected]
> 
> Joana Quina
> 
> > My problem is that -xtdes- says my two key variables do not together
> > uniquely identify the cases in my large panel data set. I am working
> > with a small panel (N=32 and T=4).
> >
> > I have no duplicates, though "duplicates report" wrongly says I have
> > one dupliacate observation. Curiously, "duplicates list" correctly
> > says I have none.
> > This appears to have happened to the only other query I could find on
> > this subject. I have tried changing width, but stata says "option
> > width() not allowed".
> >
> > I don't know what else to do. It seems quite a ridiculous problem for
> > such a small data set! Thank you in advance for any pointers.
> >
> > Joana
> >
> > PS - I have Stata 8
> 
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