[R] glmmPQL and variance structure
patrick.giraudoux at univ-fcomte.fr
Sat Jan 7 12:07:20 CET 2006
On the line of a last (unanswered) question about glmmPQL() of the
library MASS, I am still wondering if it is possible to pass a variance
structure object to the call to lme() within the functions (e.g.
weights=varPower(1), etc...). The current weights argument of glmmPQL is
actually used for a call to glm -and not for lme). I have tried to go
through the code, and gathered that the variance structure passed to the
call to lme() was:
mcall$weights <- quote(varFixed(~invwt))
and this cannot be modified by and argument of glmmPQL().
I have tried to modify the script a bit wildly and changed varFixed
into VarPower(~1), in a glmmPQL2 function. I get the following error:
> glmmPQL2(y ~ trt + I(week > 2), random = ~ 1 | ID,
+ family = binomial, data = bacteria)
Error in unlist(x, recursive, use.names) :
argument not a list
I get the same error whatever the change in variance structure on this line.
Beyond this I wonder why variance structure cannot be passed to lme via
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