Restricting parameters: "AR is not defined".

For technical questions regarding estimation of single equations, systems, VARs, Factor analysis and State Space Models in EViews. General econometric questions and advice should go in the Econometric Discussions forum.

Moderators: EViews Gareth, EViews Moderator

E-Conman
Posts: 17
Joined: Sat Feb 28, 2015 5:09 am

Restricting parameters: "AR is not defined".

Postby E-Conman » Wed Apr 12, 2017 4:47 pm

I estimated a model in eviews, but I want to tweak the parameters a bit to my liking prior to exporting the residuals.

The model is the following simple AR-model:

Y ar(25)

And after estimation I have made the judgement that the estimation is biased and want to modify it so that the parameter is restricted in the following way:

Y = 0.46*ar(25)

Which yields me the "Ar is not defined" error. There is also a secondary issue, eviews won't let me estimate this sort of equation since there is no parameter to estimate, yet I still want to obtain the residuals. Is there a way to accomplish what I attempted here in eviews?

EDIT: I think I got the right form:

[AR(25) = 0.46] in the place of AR. Still having the issue with no parameters specified.

startz
Non-normality and collinearity are NOT problems!
Posts: 3775
Joined: Wed Sep 17, 2008 2:25 pm

Re: Restricting parameters: "AR is not defined".

Postby startz » Wed Apr 12, 2017 5:37 pm

Your model appears to be
y = .46*y(-25)

in which case the residuals are going to be
y - .46*y(-25)

E-Conman
Posts: 17
Joined: Sat Feb 28, 2015 5:09 am

Re: Restricting parameters: "AR is not defined".

Postby E-Conman » Thu Apr 13, 2017 2:31 am

Well, yes, but I would like to do the same thing with an MA model and different combinations of AR and MA terms, then the solution involves solving difference equations which is a bit of a headache. Much easier to just constrict the parameters and estimate the model...

startz
Non-normality and collinearity are NOT problems!
Posts: 3775
Joined: Wed Sep 17, 2008 2:25 pm

Re: Restricting parameters: "AR is not defined".

Postby startz » Thu Apr 13, 2017 6:15 am

I don't think that EViews has any way to constrain ARMA parameters.

EViews Glenn
EViews Developer
Posts: 2672
Joined: Wed Oct 15, 2008 9:17 am

Re: Restricting parameters: "AR is not defined".

Postby EViews Glenn » Tue Apr 18, 2017 1:02 pm

The only way to do it is to transform to the equivalent nonlinear specification yourself.

startz
Non-normality and collinearity are NOT problems!
Posts: 3775
Joined: Wed Sep 17, 2008 2:25 pm

Re: Restricting parameters: "AR is not defined".

Postby startz » Tue Apr 18, 2017 1:17 pm

EViews Glenn wrote:The only way to do it is to transform to the equivalent nonlinear specification yourself.

That's not so easy with an MA model.

EViews Gareth
Fe ddaethom, fe welon, fe amcangyfrifon
Posts: 13313
Joined: Tue Sep 16, 2008 5:38 pm

Re: Restricting parameters: "AR is not defined".

Postby EViews Gareth » Tue Apr 18, 2017 2:07 pm

If all you want is the forecasted values (or fitted values) from a restricted ARMA model, without estimating any parameters at all, you can use the model object.

Put your estimated equation into the model, then break the links on that equation in the model and modify the coefficients to be whatever values you want.
Follow us on Twitter @IHSEViews

startz
Non-normality and collinearity are NOT problems!
Posts: 3775
Joined: Wed Sep 17, 2008 2:25 pm

Re: Restricting parameters: "AR is not defined".

Postby startz » Tue Apr 18, 2017 2:37 pm

Clever.


Return to “Estimation”

Who is online

Users browsing this forum: Baidu [Spider] and 19 guests