[R] Variance Functions in lme

Andrew Robinson A.Robinson at ms.unimelb.edu.au
Thu Nov 9 21:28:23 CET 2006


most likely, either by using the varIdent class, or conditioning the
varPower class on sex. See p. 177, and 208-225 of Pinheiro and Bates.

As usual, it's best to frame your question so that the list can send
you some relevant code.  If you'd like a more focused answer, I
suggest that you write some code that generates a sample dataset such
as you describe below. 


On Thu, Nov 09, 2006 at 02:43:54PM -0500, Rick Bilonick wrote:
> Using the weight argument with a variance function in lme (nlme), you
> can allow for heteroscedasticity of the within-group error. Is there a
> way to do this for the other variance components? For example, suppose
> you had subjects, days nested within subjects, and visits nested within
> days within subjects (a fully nested two-way design) and you had, say
> men and women subjects. Could you allow for differences in the variance
> components for men and women?
> Rick B.
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Andrew Robinson  
Department of Mathematics and Statistics            Tel: +61-3-8344-9763
University of Melbourne, VIC 3010 Australia         Fax: +61-3-8344-4599

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