Re: st: Re: Questions on Stata

[Ernest Berkhout <Ernest.Berkhout@seo.nl>]

At 13:58 13/12/2004, you wrote:
> Sorry, please ignored the previous message about var4
>
> egen var4 = group(var2)
> bysort var2 : gen var5 = _n
Still not generally applicable!
First, one should start by using informative variable names, so that 'var2' 
would become 'age'. This makes problems more straightforward, the current 
problem appears immediately: what is two persons have the same age?

The original poster should better examine the possibilities of -generate- 
in combination with explicit subsscripting. If it is the case (and only 
then!) that every person in the dataset had 3 records and they are stored 
directly on top of eachother, than you can generate a person-identifier 
(variable 'personid') and some individual counter (variable 'time'):

gen id = ceil(_n/3)
bysort id: gen time = _n

However, this is a dangerous practice imho. How can one be sure that each 
person is measured exactly 3 times, and that there are no missing 
observations? Why is there no id-variable already included?


Ernest Berkhout
SEO Amsterdam Economics
University of Amsterdam
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