[R] Using varPower in gnls, an answer of sorts.

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Mar 2 23:28:41 CET 2005

On Wed, 2 Mar 2005 Setzer.Woodrow at epamail.epa.gov wrote:

> Back on January 16, a message on R-help from Ravi Varadhan described a
> problem with gnls using weights=varPower().  The problem was that the
> fit failed with error


> I'm sending this to r-help rather to the authors of nlme because I am
> not sure where the bug is: is model.frame misbehaving, or should gnls
> not include '.' in its call to model.frame?

'.' is only defined in a formula for model.frame() when there is a 'data' 
argument (otherwise what do you think it might mean?).  So this is not a 
problem in model.frame(), hence on your analysis in gnls() or the usage of 

Brian D. Ripley,                  ripley at stats.ox.ac.uk
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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