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Multistage Dose-Response Model with Quadratic Terms

Source: R/multi2.R
multi2.Rd

A five-parameter multistage dose-response model 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.

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

A list containing the nonlinear function, the self starter function, and the parameter names.

Details

The multistage model function with quadratic terms is:

$$f(x) = c + (d-c)\exp(-b1 - b2 x - b3 x^2)$$

where x denotes the dose or the logarithm-transformed dose.

References

Wheeler, M. W., Bailer, A. J. (2009) Comparing model averaging with other model selection strategies for benchmark dose estimation, Environmental and Ecological Statistics, 16, 37–51.

Author

Christian Ritz