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"Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 6:49 am
by thomaskm
Dear forum participants,
My goal is to measure inflation persistence for a set of countries. The set of countries is divided into two sections: 'Discretionary countries' and 'Rule based countries'
I use the following regression specification:
d(inflation)=c+b1d(inflation(-1)).
My problem is: i want to find two values of b1. One for all the discretionary countries, and one for all the rule based countries.
I know that what i can't do is take the average of all the seperate regression coefficients of b1.
I don't want to aggregate the inflation data for the set of countries, as some countries (obviously) have higher inflation than other countries, so that would induce a higher weight in the measurement for high inflation countries compared to low inflation countries.
Is there any other way to find two seperate values of b1? Help would be greatly appreciated!
Kind Regards,
Thomas
"Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 7:14 am
by startz
Create a dummy variable for the two sets of countries. Then add in the dummy and an interaction term.
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 7:23 am
by thomaskm
So the dummy would look something like this? d:=1 if discretionary, 0 if rule-based. ?
How do I add in a dummy in Eviews? I thought of this option before but i couldn't find any tutorial anywhere on using dummies in Eviews. I'm quite new to Eviews and time series in general.
Is there any chance you can show me what the procedure is so I know how to do it? The eviews file is attached in my first message, if you want to fill it out there.
Your help is much appreciated.
Thomas
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 7:35 am
by startz
So the dummy would look something like this? d:=1 if discretionary, 0 if rule-based. ?
How do I add in a dummy in Eviews? I thought of this option before but i couldn't find any tutorial anywhere on using dummies in Eviews. I'm quite new to Eviews and time series in general.
Thomas
You have it right.
A dummy variable is no different from any other variable. You may have to set up a panel structure since you have both a cross-country and time series dimension.
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 8:26 am
by thomaskm
Thanks for you advice. Looks like i got a lot further now.
I stacked the data as the tutorial describes here:
http://forums.eviews.com/viewtopic.php?t=74&f=7
Then, I did a regression including the dummy variable on the entire dataset. I used a dummy: d1=1 if Rule based, d1=0 if Discretionary.
The output is in the attachment (check regression: inflation_persistence, i used first difference to achieve stationarity).
Could you please tell me if i did the regression right, or if i'm missing something.
In case i did it right, would the following interpretation of the regression be right?
b1=0.616 for rule-based countries and 0.616-0.0556 for discretionary countries.
Thanks a lot for your help so far,
Thomas
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 9:06 am
by startz
Unfortunately, I don't have access to EViews at the moment.
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 9:11 am
by thomaskm
I see, here's a screenshot then!

Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 9:15 am
by startz
You're interpreting it correctly, but I would recommend including the dummy on its own as well as the interaction.
Re: "Averaging" many to just 1 coefficient in OLS.
Posted: Thu Jun 28, 2012 11:24 am
by thomaskm
Thank you so much for your quick and helpful responses today, you've been a great help!
Kind regards,
Thomas