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VAR(1)
Posted: Sat Mar 06, 2010 2:55 am
by kristin
Hi Everybody,
I want to replicate a study including VAR-models.
It is said that the following VAR(1) was estimated
Δy(t)=µ+Πy(t-1)+ε(t)
I learned that in a VAR the variables on the left hand side and on the right hand side have to be the same, so that you must have Δy(t-1) on right hand side when you have Δy(t) on the left hand side (what is exactly that what appears when I estimate the model in EViews.
Many thanks in advance for any help.
Re: VAR(1)
Posted: Sat Mar 06, 2010 12:40 pm
by EViews Gareth
If there is a question here, it isn't immediately clear what it is...
Re: VAR(1)
Posted: Sun Mar 07, 2010 4:07 am
by kristin
Ok. I'm sorry. I try to make myself clear.
I have an ouput table that I want to replicate.
On top of the tabe it is said that the following bivariate VAR(1) is estimated:
Δy(t)=µ+Πy(t-1)+ε(t).
The output containts one equation for Δf(t) and one for Δs(t):
Δf(t)=0.009-1.771*f(t-1)+1.744*s(t-1)+ε(ft)
Δs(t)=0.009-1.676*f(t-1)+1.649*s(t-1)+ε(st).
I tried to estimate it in EViews with "Estimate VAR" or "Estimate VEC" and entered Δf(t) and Δs(t) as endogenous variables. But I never get an output like the one mentioned above as the right hand side of a VAR contains the lagged endogenous variables Δf(t-1) and Δs(t-1) and not f(t-1) or s(t-1).
So my question is how I can estimate the equations above. If I can just estimate them separately with "ls" or if I would miss important dynamics doing so.
Or do I have to estimate a VEC without including lags?!
Re: VAR(1)
Posted: Sun Mar 07, 2010 12:36 pm
by EViews Gareth
Not sure I follow that - assuming you're using Δf(t) to stand for differencing, if you enter a difference term as one of the left hand side variables, EViews will report difference terms on the right hand side too.
Re: VAR(1)
Posted: Sun Mar 07, 2010 1:39 pm
by kristin
That's the problem. I need differences on the left side, but not on the right side.
Re: VAR(1)
Posted: Sun Mar 07, 2010 2:30 pm
by EViews Gareth
Ah I understand now. You won't be able to do that in a VAR object. You'll have to use a System instead.
Re: VAR(1)
Posted: Sun Mar 07, 2010 2:41 pm
by kristin
It confused me that the guy in my study called it VAR.
Will I miss important dynamics if I estimate a System instead of a VAR?
Re: VAR(1)
Posted: Sun Mar 07, 2010 3:22 pm
by EViews Gareth
The coefficient estimates will be the same. You'll lose some post-estimation diagnostics (notably impulse responses).
Re: VAR(1)
Posted: Tue Mar 09, 2010 1:04 am
by Steffen
I have a question that might fit into this context.
I want to estimate the VECM:
Δs(t+1)=α(s)*[f(t)-β(s)s(t)-µ]+ε(s,t+1)
Δf(t+1)=α(f)*[f(t)-β(s)s(t)-µ]+ε(f,t+1)
Can I estimate this with "Estimate VAR" or do I also have to choose a system?
If I can estimate it with "Estimate VAR" (choosing VEC), how can I estimate the above equation with the paranthesis?