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Re: st: generating a 0,1 variable which depends on lag values


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: generating a 0,1 variable which depends on lag values
Date   Wed, 11 Sep 2002 23:51:17 +0100

Nisha Malhotra

> I am facing a problem creating a binary variable.  I have a large
panel data
> set. The three important variables are Year, Industry, Action taken
by an
> industry ( variable that takes the value 0 if no action was taken
and 1 if one
> action was taken and 2 if two actions were taken and so on )
>
> The data looks something like this
> Year  Industry  Action
> 90        A       0
> 91        A       0
> 92        A       2
> 93        A       0
> 90        B       1
> 91        B       0
> 92        B       0
> 93        B       1
>
> I want to create a binary variable say BB, which takes the value 0
if no prior
> action(in the previous years) has been taken by an industry and 1 if
some
> positive action has been taken by an industry in the previous years.
>
> Year  Industry  Action   BB
> 90        A       0       0
> 91        A       0       0
> 92        A       2       1
> 93        A       0       1
> 90        B       1       1
> 91        B       0       1
> 92        B       0       1
> 93        B       1       1

. tsset Industry year

Note that if Industry is really string, you must -encode- it
first and use the encoded version as panel variable.

. gen byte BB = L.Action > 0 & L.Action < .

Here the attitude over the first value of BB for each
Industry differs from your example.


Nick
n.j.cox@durham.ac.uk

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