Hello,

I'm interested in finding common values from a variable corresponding to two different values in another variable. For example, given two variables country_name and product_export_id as follows:
country_name product_export_id
USA 1001
USA 1201
China 1230
China 1001
I am interested in knowing the common product_export_id for USA and China and how many they are. Something like USA and China export only 1 product that is the same and what that product's product_export_id is.

Can anyone please help me do this in stata? I later want to be able to create an index using this information.
Any help will be much appreciated.

Thank you!