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Re: st: Newbie question on creating variable


From   David Kantor <dkantor@jhu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Newbie question on creating variable
Date   Mon, 01 Mar 2004 15:45:54 -0500

Try this:

egen byte n1 = sum(year==1970) , by(countrycode)
assert n1==1 // make sure only one per country
drop n1

gen int temp1 = gdp if year==1970
egen int gdp1970 = max(temp1) by(countrycode)
drop temp1
gen int diff = gdp1970 -gdp


I assumed that int is a good type for gdp.

Also, the first part assures that there is exactly one case with year==1970 per country. You could be a bit more general and assure that there is at most one case (assert n1<=1).

Maybe there is some other obvious solution I've overlooked.

I hope this helps.
-- David

At 02:14 PM 3/1/2004 -0500, AmBush (Kakatua Kutta) wrote:

countrycode year gdp
BAN 1960 65
BAN 1965 75
BAN 1970 85
CAN 1960 25
CAN 1965 35
CAN 1970 45

Dear Stata users,
Lets say I have the above data set. I want to create a variable which measures the difference between the gdp in year 1970 and gdp in 1965 for each country. That is if "diff" is the new variable it would be diff = gdp(1970)-gdp (1965) for each country.
I am a new user and already spent hours on this. I would much appreciate your help.
Thanks in advance
AmBush
[...]
David Kantor
Institute for Policy Studies
Johns Hopkins University
dkantor@jhu.edu
410-516-5404

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