| W1.4 {drc} | R Documentation |
'W1.4' and 'W2.4' provide the four-parameter Weibull functions, self starter function and names of the parameters.
W1.4(fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"))
W2.4(fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"))
fixed |
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed. |
names |
a vector of character strings giving the names of the parameters. The default is reasonable. |
The equations for the mean functions are given at weibull1.
See weibull1.
This function is for use with the model fitting function drm.
Christian Ritz
Seber, G. A. F. and Wild, C. J (1989) Nonlinear Regression, New York: Wiley & Sons (pp. 330–331).
Setting c=0 yields W1.3. A more flexible function, allowing
fixing or constraining parameters, is available through weibull1.
## Fitting a four-parameter Weibull (type 1) model terbuthylazin.m1 <- drm(rgr~dose, data = terbuthylazin, fct = W1.4()) summary(terbuthylazin.m1)