Three-parameter Weibull (type 2) model

A three-parameter Weibull type 2 model with the lower limit fixed at 0. The model is given by the equation $$f(x) = d \cdot (1 - \exp(-\exp(b(\log(x) - \log(e)))))$$

Usage

W2.3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), ...)

Arguments

fixed

numeric vector of length 3, specifying fixed parameters (use NA for parameters that should be estimated).

names

character vector of length 3 giving the names of the parameters (default c("b", "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.

Value

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

See also

weibull2, W2.2, W2.4

Examples

ryegrass.m1 <- drm(rootl ~ conc, data = ryegrass, fct = W2.3())