st: combining data sets with different dimensions

[Kremena Platikanova <Kremena.Platikanova@colorado.edu>]

Hi,

I want to combine the following four data sets:

Data set 1:
importer   exporter   year   commodity_code   commodity_value
(for example,
USA        Canada     2003      0001             .....
USA        Canada     2003      0002             .....
USA        Canada     2003      0003             .....
USA        Canada     2004      0001             .....
USA        Canada     2004      0004             .....)

Data set 2:
importer   year   gdp_importer

Data set 3:
exporter   year   gdp_exporter

Data set 4:
importer   exporter   geograph_distance

Basically, I want to add the variables:
gdp_importer, gdp_exporter and geograph_distance (between importer and
exporter) to data set 1.

How can I do that given the difference in the dimesions of the data sets?

Thank you for yor help,

Kremena
--
Kremena Platikanova
Ph.D. Candidate
Department of Economics
University of Colorado, Boulder
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