drc (version 2.5-12)

multi2: Multistage dose-response model with quadratic terms

Description

The multistage dose-response model is a combination of log-logistic models that should be useful for describing more complex dose-response patterns.

Usage

multi2(
  fixed = c(NA, NA, NA, NA, NA), 
  names = c("b1", "b2", "b3", "c", "d"), 
  ssfct = NULL, 
  fctName, 
  fctText)

Arguments

fixed

numeric vector specifying which parameters are fixed and at what value they are fixed. NAs are used for parameters that are not fixed.

names

a vector of character strings giving the names of the parameters (should not contain ":"). The default is reasonable (see under 'Usage').

ssfct

a self starter function to be used.

fctName

optional character string used internally by convenience functions.

fctText

optional character string used internally by convenience functions.

Value

• The value returned is a list containing the nonlinear function, the self starter function and the parameter names.

Details

The multistage model function with quadratic terms is defined as follows $$f(x) = c + (d-c)\exp(-b1-b2x-b3x^2)$$ where x denotes the dose or the logarithm-transformed dose.

References

NN