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First differenced equation

Posted: Fri Dec 26, 2014 7:49 am
by johnf
Hi,

Can someone please help a beginner with the example from the book of Wooldridge "Introductory econometrics: a modern approach", 5th edition, page 462, equation 13.18. I don't know how to get those coefficients? He was using CRIME2.RAW file (in the attachment).

The first differenced estimated equation from the book looks like this: Δcrmrte = 15.40 + 2.22 Δunem.

I've been using following commands and OLS: D(crmrte) c D(unem).

What am I missing?

Many thanks.

Re: First differenced equation

Posted: Fri Dec 26, 2014 8:31 am
by startz
You need to look more carefully at how your data is organized. Hint: How many observations do you have compared to Wooldridge?

Re: First differenced equation

Posted: Fri Dec 26, 2014 9:05 am
by johnf
There are total 92 observations in the CRIME2.RAW - crmrte and unem.

Re: First differenced equation

Posted: Fri Dec 26, 2014 9:35 am
by startz
How many observations in the textbook equation?

Re: First differenced equation

Posted: Fri Dec 26, 2014 11:14 am
by johnf
If am right, what I actually need to do is to subtract row2-row1, row4-row3, etc. from crmrte and unem?

Can you help to do this in EViews?

Re: First differenced equation

Posted: Fri Dec 26, 2014 12:28 pm
by startz
You probably want to set the sample to only include certain observations. Take a look at the smpl if command.

Re: First differenced equation

Posted: Fri Dec 26, 2014 1:51 pm
by johnf
Can you please suggest how to include every second value with smpl if?