Re: [R] lme: random effects of a quadratic term

From: Marc Schwartz <>
Date: Sun 27 Mar 2005 - 07:37:31 EST

On Sat, 2005-03-26 at 22:21 +0100, Montse Rue wrote:
> I tried to replicate in R the example that Pinheiro and Bates present
> on section 1.5 of their mixed-effects book, the pixel intensity
> example.
> > fm1Pixel<-lme(pixel~day+day^2,data=Pixel,random=list(Dog=~day,Side=~1))
> When I run it in R the second order term does not appear in the
> estimated model. But, when I write
> > fm1Pixel<-lme(pixel~day+I(day^2),data=Pixel,random=list(Dog=~day,Side=~1))
> I get the same results as in the Pinheiro and Bates book, and the plot
> of the augPred values is a quadratic function as in Figure 1.18. The
> same happens with my data when I use the I(alcadakm^2) .
> Can it be that S accepts day^2 but R doesn't?
> Thanks again!
> Montse

<SNIP of prior exchange>

As per the main R FAQ "3.3.2 Models":

There are some differences in the modeling code, such as

Please read the FAQ's when comparing R and S[-PLUS] as this is but one of the important differences:

Marc Schwartz mailing list PLEASE do read the posting guide! Received on Sun Mar 27 07:42:09 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:30:56 EST