Re: [Gretl-users] Creating variables
On Wed, 10 Jun 2009, Data Analytics Corp. wrote:
Hi,
I'm new to GRETL so please excuse the following naive question.
Welcome!
How do I create a new variable in a script? Here's my problem.
I have
a monthly times series from 1960:1 to 2009:4. One variable is the
monthly cpi. I merely want to calculate the percent change on an annual
basis. I used the following:
genr pct = (((cpi/lags(1, cpi))^12)-1)*100
the "lags" function returns a _list_ of variables. To lag an existing
series, you just use the "x(-n)" syntax, as in
genr pct = (((cpi/cpi(-1))^12)-1)*100
note, however, that there are several ways to accomplish the above, like
for instance
genr pct = 100*exp(12*ldiff(cpi)-1)
that I personally find cleaner.
Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche
r.lucchetti(a)univpm.it
http://www.econ.univpm.it/lucchetti