st: Identify Panel Structure of Dataset

[Katharina.Eck@lrz.uni-muenchen.de]

Hi all,

I have compiled a dataset with firm-product-year information, e.g.:


Firm      Product           t    Salesvalue
A              1          2000     5000
A              1          2001     5500

A              2          2000     3000
A              2          2001     3500
A              2          2002     4000

B              3          2001      500
B              3          2002      550
B              3          2003      710

B              4          2001     2000
B              4          2002     4000
...
Basically, firms have different products and report info on their products
for different years. Firm A has info for the years 2000-2001 (Product 1)
and for 2000-2002 (Product 2) while B reports on Product 3 in 2001-2003
and in 2001-2001 on Product 4.
I want to find out which time horizon I should use for my panel to get the
longest time horizon possible. In this example, I would use t=2001,2002
since both, A and B report in both years.

How can I do this in Stata?


Thank you for your help!

Katharina

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