[R-sig-eco] CLMM and model selection conflict

[Chris.Wilcox at csiro.au]

Hi all,

I am using CLMM in package ordinal to model the condition of animal carcasses (on a 1 – 5 scale of decay) in an experiment evaluating the relationship between time since death and condition.  I am fitting models to a small number of covariates (5) in addition to the time.  We followed the condition of individual animal carcasses over time, in a variety of experimental conditions (on land, floating, submerged; high/low current, high/low temperature; fresh/frozen).  I want to do some model selection on the models.  I have tried add1/drop1 from the ordinal package, along with dredge from MuMIn.  In both cases the functions are not able to find a formula from the fitted model object.  After much searching, I have not found any others in the various R help mailing lists that have run into the same problem.  Any suggestions would be appreciated.

Thanks,

Chris

Chris Wilcox
Principal Research Scientist
CSIRO Marine and Atmospheric Research
Tel +61 3 6232 5306
Mob +61 4 3939 7317
www.csiro.au/Marine-debris
http://people.csiro.au/W/C/Chris-Wilcox/
http://www.imas.utas.edu.au/qms/staff-profiles/csiro-staff-profiles/dr-chris-wilcox2

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