[R] glmmPQL correlation structure

[Martin Henry H. Stevens]

Running Mac OS 10.3.5 and R 2.0
Does glmmPQL use the same spatial dependence models as gls in nmle? It 
does not seem to - I get the following, for example:
 > m2 <- glmmPQL(S.Early ~ fertilized*watered, data=geodat, 
family="poisson", random=~1|col)
iteration 1
iteration 2
 > plot(Variogram(m2, form=~col+row))
 > m3 <- update(m2,correlation=corSpher(c(5,.5), form=~col+row, 
nugget=T))
iteration 1
Error in model.frame(formula, rownames, variables, varnames, extras, 
extranames,  :
	invalid variable type
 >

Any leads on how to specify exponential or spherical models would be 
appreciated (e.g., pageg or chapter in Venables and Ripley 2002).

Cheers,
Hank


Dr. Martin Henry H. Stevens, Assistant Professor
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