W1.2 {drc} | R Documentation |
'W1.2' is the two-parameter Weibull function where the lower limit is fixed at 0 and the upper limit is fixed at 1, mostly suitable for binomial/quantal responses.
W1.2(fixed = c(NA, NA), names = c("b", "e")) W2.2(fixed = c(NA, NA), names = c("b", "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 two-parameter Weibull model is given by the expression
f(x) = exp(-exp(b(log(x)-e))).
The function is asymmetric about the inflection point, that is the parameter exp(e).
See weibull1
.
This function is for use with the function multdrc
.
Christian Ritz
Related functions are W1.3
, W1.4
, weibull1
and weibull2
.
## Fitting a two-parameter Weibull model model1 <- multdrc(number/total~dose, weights=total, data=earthworms, fct = W1.2(), type = "binomial") summary(model1) rm(model1)