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st: Identify min and max observations


From   Thomas Cars <thomas.cars@pubcare.uu.se>
To   statalist@hsphsun2.harvard.edu
Subject   st: Identify min and max observations
Date   Sun, 27 Sep 2009 14:17:38 +0200

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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