Paolo,
you might want to try this:
bysort lastname firstname dateofbirth: gen id=_n if _n==1
replace id=sum(id)
What happens to the dataset ->
1st step
Obs firstname lastname dateofbirth id
1 A B 1.1.1980 1
2 A B 1.1.1980 .
3 A B 1.1.1980 .
4 A B 1.1.1980 .
5 B C 2.2.1990 1
6 B C 2.2.1990 .
7 B C 2.2.1990 .
8 D E 3.3.2000 1
9 D E 3.3.2000 .
2nd step
Obs firstname lastname dateofbirth id
1 A B 1.1.1980 1
2 A B 1.1.1980 1
3 A B 1.1.1980 1
4 A B 1.1.1980 1
5 B C 2.2.1990 2
6 B C 2.2.1990 2
7 B C 2.2.1990 2
8 D E 3.3.2000 3
9 D E 3.3.2000 3
(I learnt this way from the following book, which unfortunately available only in German:
Kohler U: Datenanalyse mit Stata. M�nchen, Wien. Oldenbourg 2001)
Kind regards,
sebastian
> -----Urspr�ngliche Nachricht-----
> Von: [email protected]
> [mailto:[email protected]] Im Auftrag von
> Paolo Grillo, MD
> Gesendet: Freitag, 4. Februar 2005 10:13
> An: [email protected]
> Betreff: st: create unique variables
>
>
> I have a dataset with the following variables:
>
> last name
> first name
> date of birth
>
> Since this dataset contains more than one record for
> individual, I would
> create a unique variable for subject (ID).
> Could anyone help me in this problem?
> Thank in advance
>
> --
>
>
>
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>
> Paolo Grillo MD
> Nephrologist
> Statisticians
> EPOCA Research Center for Occupational, Clinical &
> Environmental Epidemiology Department of Occupational and
> Environmental Health "Clinica L. Devoto" University of Milan
> Via San Barnaba 8 20122 Milano - ITALY
> Tel: +39 02 503-20148
> Fax: +39 02 503-20126
> E-Mail [email protected]
>
>
>
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>
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