Just a thought, you may have a 3-dimensional panel because only id and year
cannot give you an unique observation (such as firm id is nested within
segment id). But, -duplicates- searches all the variables, not only id and
year. What I'm saying is that there is no conflict here. See Nick's message.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Joana Quina
Sent: Tuesday, July 05, 2005 4:43 PM
To: [email protected]
Subject: Re: st: RE: not uniquely identified observ in small panel
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
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
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* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
