# varFixed

0th

Percentile

##### 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
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.