Are the years equally spaced and in time order?
If so, it probably doesn't matter, and if not you may want corCAR1 not corAR1.



On Thu, 10 Feb 2005, David Hugh-Jones wrote:

Assuming I have years in YEAR and state ids in ID, I guess the
correlation ought to be

corAR1(form = ~ YEAR | ID)

?

Thanks a lot,
David




On Thu, 10 Feb 2005 12:36:32 -0500, Doran, Harold <[EMAIL PROTECTED]> wrote:
In the nlme package you can find the gls() function to account for
autocorrelation over time using corAR1. Syntax might look something like
this:

fm1 <- gls(response ~ IV, long, correlation=corAR1(form=~1|ID),
method='ML')

You can also use weights() for heteroscedasticity.

-Harold

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of David Hugh-Jones
Sent: Thursday, February 10, 2005 12:15 PM
To: [email protected]
Subject: [R] correcting for autocorrelation in models with panel data?

Hi

I have some panel data for the 50 US states over about 25 years, and I
would like to test a simple model via OLS, using this data. I know how
to run OLS in R, and I think I can see how to  create Panel Corrected
Standard Errors using

http://jackman.stanford.edu/classes/350C/pcse.r

What I can't figure out is how to correct for autocorrelation over time.
I have found a lot of R stuff on time series models but they all seem
focused on predicting a single variable from its previous values.
Can anyone explain to me how to detect and get round autocorrelation?
Is there a package for panel data that I have missed?

I appreciate that this is probably just as much about my ignorance of
econometrics as about R itself!

Cheers
David

-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595

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