gammadr: Gamma dose-response model

In drc: Analysis of Dose-Response Curves

Description

The gamma dose-response model is a four-parameter model derived from the cumulative distribution function of the gamma distribution.

Usage

  gammadr(fixed = c(NA, NA, NA, NA), 
  names = c("b", "c", "d", "e"), 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').
fctName	optional character string used internally by convenience functions.
fctText	optional character string used internally by convenience functions.

Details

Following Wheeler and Bailer (2009) the model function is defined as follows:

f(x) = c + (d-c) * pgamma(b*x, e, 1)

This model is only suitable for increasing dose-response data.

Value

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

Author(s)

Christian Ritz

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.

drc documentation built on May 1, 2019, 8:43 p.m.