varFixed

Fixed Variance Function

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 \(\sigma^2(v)\) for this class is \(\sigma^2(v)=|v|\). The variance covariate \(v\) is evaluated once at initialization and remains fixed thereafter. No coefficients are required to represent this variance function.

Keywords
models
Usage
varFixed(value)
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.

References

Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer.

See Also

varClasses, varWeights.varFunc, varFunc

Aliases
  • varFixed
Examples
# NOT RUN {
vf1 <- varFixed(~age)
# }
Documentation reproduced from package nlme, version 3.1-145, License: GPL (>= 2) | file LICENCE

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