[R] glmmPQL and variance structure
Patrick Giraudoux
patrick.giraudoux at univ-fcomte.fr
Tue Dec 27 18:44:59 CET 2005
Dear listers,
glmmPQL (package MASS) is given to work by repeated call to lme. In the
classical outputs glmmPQL the Variance Structure is given as " fixed
weights, Formula: ~invwt". The script shows that the function
varFixed() is used, though the place where 'invwt' is defined remains
unclear to me. I wonder if there is an easy way to specify another
variance structure (eg varPower, etc..), preferably using an lme object
of the varFunc classes ? Some trials show that the 'weights' argument of
glmmPQL is just the same as in glm (which is clearly stated in the help)
and I wonder actually, if not a nonsense, how to pass eg a 'weights'
arguments as used in lme (eg weights=varPower()) to specify a variance
function (in the same way as a correlation structure can be passed easy).
Thanks in advance for any hint,
Patrick
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