[Gretl-users] Creating variables

Data Analytics Corp. dataanalytics at earthlink.net
Wed Jun 10 19:38:14 EDT 2009


I'm new to GRETL so please excuse the following naive question.  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

and got

        gretl version 1.8.0
        Current session: 2009/06/10 19:29
        ? genr pct = (((cpi/lags(1, cpi))^12)-1)*100
        Data types not conformable for operation

        Error executing script: halting
        > genr pct = (((cpi/lags(1, cpi))^12)-1)*100

What's wrong?  What's conformability have to do with this?  Conformable 
on what?  Also, I did the following:

        genr lag = lags(1, cpi)

and got
        gretl version 1.8.0
        Current session: 2009/06/10 19:32
        ? genr lag = lags(1, cpi)
        Generated list lag

but lag was no where in my variable list, although cpi(-1) was.  Can 
someone explain how variables are created?

Any help is appreciated.




Walter R. Paczkowski, Ph.D.
Data Analytics Corp.
44 Hamilton Lane
Plainsboro, NJ 08536
(V) 609-936-8999
(F) 609-936-3733
dataanalytics at earthlink.net

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