Two-parameter Weibull type 1 model

A two-parameter Weibull type 1 model with the lower limit fixed at 0 and the upper limit fixed at a specified value (default 1).

Usage

W1.2(upper = 1, fixed = c(NA, NA), names = c("b", "e"), ...)

w2(upper = 1, fixed = c(NA, NA), names = c("b", "e"), ...)

upper: numeric value giving the fixed upper limit. The default is 1.
fixed: numeric vector of length 2. Specifies which parameters are fixed and at what value. Use NA for parameters that are not fixed.
names: character vector of length 2 giving the names of the parameters. The default is c("b", "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 $$f(x) = upper \exp(-\exp(b(\log(x) - \log(e))))$$

This is mostly used for binomial/quantal responses.

earthworms.m1 <- drm(number/total ~ dose, weights = total,
  data = earthworms, fct = W1.2(), type = "binomial")