Four-parameter Weibull (type 2) model

A four-parameter Weibull type 2 model. The model is given by the equation $$f(x) = c + (d - c)(1 - \exp(-\exp(b(\log(x) - \log(e)))))$$

Usage

W2.4(fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"), ...)

fixed: numeric vector of length 4, specifying fixed parameters (use NA for parameters that should be estimated).
names: character vector of length 4 giving the names of the parameters (default c("b", "c", "d", "e")).
...: additional arguments passed to weibull2, most notably method (a character string: "1" (default), "2", "3", or "4") which selects the self-starter method for obtaining starting values. See weibull2 for details.

A list of class "Weibull-2" as returned by weibull2.

terbuthylazin.m1 <- drm(rgr ~ dose, data = terbuthylazin, fct = W2.4())