bread.drc {drc} | R Documentation |
Bread and meat for the sandwich estimator of the variance-covariance.
bread.drc(x, ...) estfun.drc(x, ...)
x |
object of class drc |
... |
additional arguments. At the moment none are supported. |
More explanations are found in Zeileis (2006).
The unscaled hessian is returned by bread.drc
, whereas estfun.drc
returns the estimating function evaluated at the data and the parameter estimates.
Christian Ritz
Zeileis, A. (2006) Object-oriented Computation of Sandwich Estimators, J. Statist. Software, 16, Issue 9.
For other applications see sandwich
.
## 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)