At 08:47 PM 9/7/2004 -0500, Kang, Eugene wrote:
Hi,
I have a cross-section panel data that is unbalanced. For instance:
id year x1
111 1999 3
111 2000 5
111 2001 6
123 2000 4
123 2001 2
For the above example, there are 2 unique ids (111 and 123). Since my
dataset has over 6000 observations, what commands should I use to generate a
count of unique ids?
One of many possible approaches:
. egen x = group(id)
. sum x
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
x | 5 1.4 .5477226 1 2
The value for Max is the # of unique ids.
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
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