Fractional polynomial-logistic dose-response models

Model function for specifying dose-response models that are a combination of a logistic model and an appropriate class of fractional polynomials.

fplogistic(p1, p2, fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"),
method = c("1", "2", "3", "4"), ssfct = NULL, fctName, fctText)

FPL.4(p1, p2, fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"), ...)

Arguments

p1	numeric denoting the negative power of log(dose+1) in the fractional polynomial.
p2	numeric denoting the positive power of log(dose+1) in the fractional polynomial.
fixed	numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter 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'). The order of the parameters is: b, c, d, e, f (see under 'Details').
method	character string indicating the self starter function to use.
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.
...	Additional arguments (see fplogistic).

Details

The fractional polynomial dose-response models introduced by Namata et al. (2008) are implemented using the logistic model as base.

Value

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

References

Namata, Harriet and Aerts, Marc and Faes, Christel and Teunis, Peter (2008) Model Averaging in Microbial Risk Assessment Using Fractional Polynomials, Risk Analysis 28, 891--905.

See also

Examples are found on the hep page of maED.