| ml4a {drc} | R Documentation |
'ml4a' provides Cedergreen-Ritz-Streibig's modified logistic dose response function.
ml4a(names = c("b", "c", "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) = c + frac{d-c+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 ml4b and ml4c.
## Modified logistic model model1 <- multdrc(hormesis[,c(2,1)], fct=ml4a()) summary(model1) ED(model1, c(50)) rm(model1)