If I want to test if X Granger-cause Y, both should be endogenous a priori.
You test if X or Y is "weak exogenous", for example, testing for the
coefficient of the ECM. You probably should read more about it in, e.g.,
Enders (2004) or other good time series textbook.
Best Wishes,
Claudio D. Shikida
Obrigado por seu tempo e atenção!
Claudio D. Shikida
http://www.shikida.net and
http://works.bepress.com/claudio_shikida/
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On Wed, Oct 31, 2012 at 4:11 PM, 佃鹏 于 <dianpenginuk(a)live.cn> wrote:
Hi, Gretl team,
I have run the Granger Causality in Gretl using VAR, after that I found
there are unit roots in variables. So I changed to VECM model to test the
causality between variables for example in following equation: Y =X1+X2+X3.
I input Y as endogenous variable and X1 X2 X3 as exogeous variables. But
the results didn't come up, it shows “You must select two or more
endogenous variables” But in the original regression equation only Y is
endogenous variable. why it shows that?
Does it make any difference for the results of Granger Causality if there
are unit roots in variables? what should I avoid them instead of using
VECM in Gretl?
Thank you for your time
Dianpeng YU
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