varFixed(value)
value
|
a one-sided formula of the form ~ v specifying a
variance covariate v . Grouping factors are ignored.
|
varFixed
class,
representing a variance function with fixed variances. Letting v
denote the variance covariate defined in value
, the variance
function s2(v) for this class is
s2(v)=|v|. The variance covariate v is
evaluated once at initialization and remains fixed thereafter. No
coefficients are required to represent this variance function.varFixed
object representing a fixed variance function
structure, also inheriting from class varFunc
.varWeights.varFunc
, varFunc
library(lme) vf1 <- varFixed(~age)