Strange formula in pooled model

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kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Strange formula in pooled model

Postby kiber_master » Tue Apr 02, 2013 8:10 am

Hello!

I tried to calculate pooled model (without effects) with AR and SAR, and found out that fitted in "Actual, Fitted, Residual Table" differs from static forecast on the same period. I then discovered that the formula for fitted series for pooled model in EViews differs from the same formula for linear regression (also with AR and SAR) by one summand.
I've prepared an example for you in workfile and calculation in Excel, so you can see the difference. Could you tell me, is there is a mistake or formula for fitted in pooled model should really be different from the same formula in linear regression?
Attachments
ols_sar.wf1
(10.43 KiB) Downloaded 369 times
pooled model formulas.xlsx
(19.12 KiB) Downloaded 469 times
pooled_sar.wf1
(12.78 KiB) Downloaded 340 times

EViews Gareth
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Re: Strange formula in pooled model

Postby EViews Gareth » Tue Apr 02, 2013 8:20 am

Might be a bug, I'll investigate. Note that the fitted value from proc->forecast, and the residual series from proc->make resid, are correct.

kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Re: Strange formula in pooled model

Postby kiber_master » Tue Apr 02, 2013 10:43 pm

the residual series from proc->make resid are the same as in "Actual, Fitted, Residual Table". So, if we named them resid01, and the fitted value from proc->forecast - fit01, their sum didn't give the actual series.
Please, check it.

EViews Gareth
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Re: Strange formula in pooled model

Postby EViews Gareth » Wed Apr 03, 2013 6:39 am

Yeah, I noticed afterwards that the residuals are not right, but forecast is.

EViews Gareth
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Re: Strange formula in pooled model

Postby EViews Gareth » Tue Apr 16, 2013 1:14 pm

This has been fixed in the latest patch.

kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Re: Strange formula in pooled model

Postby kiber_master » Thu May 30, 2013 9:55 pm

I've got it, thank you.

kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Re: Strange formula in pooled model

Postby kiber_master » Wed Jul 31, 2013 2:54 am

Sorry that I'm so late. I've check newest update of E7, and found that estimates of coefficients differs from previous version. Why is it so? Did you change something in the optimization method?
You can check it if open file poole_sar.wf1, push stats, freese the table and reestimate the model.

EViews Gareth
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Re: Strange formula in pooled model

Postby EViews Gareth » Wed Jul 31, 2013 9:40 am

There was a rare bug in panel SAR estimation that your workfile helped us spot. We fixed it.

kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Re: Strange formula in pooled model

Postby kiber_master » Wed Jul 31, 2013 8:13 pm

So, previous coefficients was not correct?

EViews Gareth
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Re: Strange formula in pooled model

Postby EViews Gareth » Wed Jul 31, 2013 8:44 pm

Right.

kiber_master
Posts: 94
Joined: Fri Sep 23, 2011 3:56 am

Re: Strange formula in pooled model

Postby kiber_master » Wed Jul 31, 2013 9:17 pm

Thank you


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