Fixed Variance Function

DESCRIPTION:

This function is a constructor for the 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.

USAGE:

varFixed(value) 

REQUIRED ARGUMENTS:

value
a one-sided formula of the form `~ v' specifying a variance covariate v. Grouping factors are ignored.

VALUE:

a varFixed object representing a fixed variance function structure, also inheriting from class varFunc.

NOTE:

You can use the functions varWeights and coef to extract the weights and coefficients, respectively, from a varFixed variance function structure. For more details, see the links below for the generic functions varWeights and coef.varFunc.

SEE ALSO:

, ,

EXAMPLES:

vf1 <- varFixed(~age)