get_starting_values: Starting values for td2pLL model

In jcduda/td2pLL: Fitting a time-dose two-parameter log-logistic model to time-dose-response data

Starting values for td2pLL model

Description

Calculates (cheap) default starting values for fitting a td2pLL model based on dose time response data.

Usage

get_starting_values(data, h_start = 2, c0_start = 0)

Arguments

data	(numeric data.frame()) Data frame with numeric columns named time, dose and resp.
h_start	(numeric(1)) Optional starting value for the h parameter. Default is 2.
c0_start	(numeric(1)) Optional starting value for the threshold parameter c0. Default is 0.

Details

As starting value for delta and gamma, a pair of cheap starting values of (dose, ED50) at the lowest and the highest (exposure) time are calculated via the interp_ED50() function. With these two pairs (dose_1, ED50_1) and (dose_2, ED50_2), as well as the set starting values of h and c0, the model equation of the td2pLL model

f(d,t)=100-100\frac{d^h}{EC_{50}(t)^h + d^h},

EC_{50}(t) = Δ \cdot t^{-γ} + C_0

is solved to get the starting values gamma_start and delta_start for gamma and delta.

Value

(list(4))
List with starting values for h, delta, gamma and c0.

jcduda/td2pLL documentation built on May 14, 2022, 6:48 p.m.