Three-parameter Weibull type 1 model

A three-parameter Weibull type 1 model with the lower limit fixed at 0.

Usage

W1.3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), ...)

w3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), ...)

fixed: numeric vector of length 3. Specifies which parameters are fixed and at what value. Use NA for parameters that are not fixed.
names: character vector of length 3 giving the names of the parameters. The default is c("b", "d", "e").
...: additional arguments passed to weibull1, most notably method (a character string: "1" (default), "2", "3", or "4") which selects the self-starter method for obtaining starting values. See weibull1 for details.

A list of class Weibull-1 containing the nonlinear function, self starter function, and parameter names.

The model is given by the expression $$f(x) = d \exp(-\exp(b(\log(x) - \log(e))))$$

This is a special case of the four-parameter Weibull type 1 model where the lower limit is fixed at 0.

ryegrass.m1 <- drm(rootl ~ conc, data = ryegrass, fct = W1.3())