st: Identify min and max observations

[Thomas Cars <thomas.cars@pubcare.uu.se>]

Hi,
I have a dataset including subjects (id) and date for administration  
of a specific drug (adm.date)

I now want to construct a variable telling me which one of the  
observations (adm.date) in each subject (id) that has the lowest date  
(min) and the highest date(max).

The number of adm.date can vary in each subject from 1 to 10.


Example (min=1 och max=2)



Id                   adm.date        min/max

1                    12may06         1
1                    20jun06
1                    30aug06         2
2                    10may06         1
2                    10sep06
2                    20dec06
2                    10jan07         2
3                    10aug06         1
3                    20sep06
3                    10dec06
3                    15jan07
3                    10feb07         2

And so on?

I hope anyone can help me!

Thomas


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