ml3a {drc} | R Documentation |
'ml3a' provides Cedergreen-Ritz-Streibig's modified logistic dose response function with the lower limit equal to 0.
ml3a(names = c("b", "d", "e", "f"), useDer = FALSE)
names |
a vector of character strings giving the names of the parameters. The default is reasonable (see above). |
useDer |
logical. If TRUE derivatives are supplied, otherwise they are not supplied. Not yet implemented! |
The model is given by the expression
f(x) = 0 + frac{d-0+f exp(-1/x)}{1+exp(b(log(x)-log(e)))}
which is a five-parameter model.
It is a modification of the four-parameter logistic curve to take hormesis into account.
See mlogistic
.
This function is for use with the function multdrc
.
Christian Ritz
Cedergreen, N. and Ritz, C. and Streibig, J. C. (2005) Improved empirical models describing hormesis, Submitted.
Similar functions are ml3b
and ml3c
.
## Modified logistic model model1 <- multdrc(hormesis[,c(2,1)], fct=ml3a()) summary(model1) ED(model1, c(50)) rm(model1)