drc (version 2.1-1)

bread.drc: Bread and meat for the sandwich

Description

Bread and meat for the sandwich estimator of the variance-covariance.

Usage

bread.drc(x, ...)
  
  estfun.drc(x, ...)

Arguments

x

object of class drc

...

additional arguments. At the moment none are supported.

Value

• The unscaled hessian is returned by bread.drc, whereas estfun.drc returns the estimating function evaluated at the data and the parameter estimates.

Details

More explanations are found in Zeileis (2006).

References

Zeileis, A. (2006) Object-oriented Computation of Sandwich Estimators, J. Statist. Software, 16, Issue 9.

See Also

For other applications see sandwich.

Examples

## The lines below requires that the packages
## 'lmtest' and 'sandwich' are installed
#library(lmtest)
#library(sandwich)

#ryegrass.m1<-drm(rootl~conc, data=ryegrass, fct=LL.4())

#coeftest(ryegrass.m1)
#coeftest(ryegrass.m1, vcov=sandwich)