Re: [R] REML with random slopes and random intercepts giving strange results

From: Doran, Harold <HDoran_at_air.org>
Date: Wed 16 Aug 2006 - 01:53:05 EST


I don't this is because you are using REML. The BLUPs from a mixed model experience some shrinkage whereas the OLS estimates would not.

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Simon Pickett
> Sent: Tuesday, August 15, 2006 11:34 AM
> To: r-help@stat.math.ethz.ch
> Subject: [R] REML with random slopes and random intercepts
> giving strange results
>
> Hi everyone,
> I have been using REML to derive intercepts and coeficients
> for each individual in a growth study. So the code is
> m2 <- lmer(change.wt ~ newwt+(newwt|id), data = grow)
>
> Calling coef(model.lmer) gives a matrix with this information
> which is what I want. However, as a test I looked at each
> individual on its own and used a simple linear regression to
> obtain the same information, then I compared the results. It
> looks like the REML method doesnt seem to approximate the two
> parameters as well as using the simple linear regression on
> each individual separately, as judged by looking at graphs.
> Indeed, why do the results differ at all?
> Excuse my naivety if this is a silly question.
> Thanks to everyone for replying to my previous questions,
> very much appreciated.
> Simon Pickett
> PhD student
> Centre For Ecology and Conservation
> Tremough Campus
> University of Exeter in Cornwall
> TR109EZ
> Tel 01326371852
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Wed Aug 16 03:15:12 2006

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Wed 16 Aug 2006 - 22:20:17 EST.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.