st: Panel data construction

[Marcello Pagano <pagano@hsph.harvard.edu>]

Posting this for Sotiris:


-------- Original Message --------

I have the following dataset :
Firm Year Country Ownership
A 1997 USA 0
A 1998 USA 1
A 1999 USA 1
B 1997 USA 0
B 1998 USA 0
B 1999 USA 1
C 1998 CAN 0
C 1999 CAN 0
......
this is a panel data that consits from many countries and 12,000 different
firms. The ownership variable is dummy with 1=foreign owned and 0=domestic
owned. The firm variable is string.

I want to create the ratio=(number of banks that are foreign owned by year
and country)/(total number of banks by year and country). In my previous
example the ratio sould look like this:
Firm Year Country Ownership ratio
A 1997 USA 0 (0/2)=0
A 1998 USA 1 (1/2)=0.5
A 1999 USA 1 (2/2)=1
B 1997 USA 0 (0/2)=0
B 1998 USA 0 (1/2)=0.5
B 1999 USA 1 (2/2)=1
C 1998 CAN 0
C 1999 CAN 0

Thank you in advance.



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