evalHillEqn: Calculate and Invert Hill Equation

In nathanieltwarog/braidrm: Fitting Dose Response with the BRAID Combined Action Model

Description

Calculates the response of a four-parameter Hill (or log-logistic) dose-response model, or determines the concentrations which yield the given response.

Usage

evalHillEqn(conc, parv)
invertHillEqn(val, parv)

Arguments

conc	a vector of concentrations to be passed as input into the model
parv	a four-element vector specifying the full parameter set of a particular Hill model
val	a vector of responses to be inverted in a particular Hill model

Details

There is some ambiguity in how the parameters of a Hill or log-logistic model are specified. We have chosen to use the following equation:

E(D) = E0 + (Ef-E0)/(1+(D/IDM)^(-n))

where the Hill slope n is always positive. Using this equation, the parameter vector for a Hill model is (n,E0,Ef,ln(IDM)) (note that the fourth parameter value is log-transformed in the parameter vector).

Value

For evalHillEqn a vector of responses resulting from the given concentrations. For invertHillEqn, a vector of concentrations that produce the given responses; responses beyond the model's maximal effect will produce a value of Inf, while responses that do not reach the model's baseline effect produce a value of 0.

Author(s)

Nathaniel R. Twarog

See Also

findBestHill, hillConcCorrect

Examples

act <- evalHillEqn(exp(seq(log(10^-8),log(10^-5),length=100)),parv=c(2,0,100,log(10^-6)))
ec90 <- invertHillEqn(90,parv=c(2,0,100,log(10^-6)))

nathanieltwarog/braidrm documentation built on May 23, 2019, 12:19 p.m.