DoseFinding (version 0.1-3)

logistic: Logistic Model

Description

The model function for the logistic model is defined as $$f(d, \theta) = E_0 + E_{\max}/\left{1 + \exp\left[ \left(ED_{50} - d \right)/\delta \right] \right}$$

Usage

logistic(dose, e0, eMax, ed50, delta)

Arguments

dose

Dose variable

e0

Left-asymptote parameter, corresponding to a basal effect level (not the placebo effect, though).

eMax

Asymptotic maximum change in effect from the basal level.

ed50

Dose giving half of the asymptotic maximum effect.

delta

Parameter controlling determining the steepness of the curve.

Value

• Response value

Details

The logistic model is intended to capture general monotone, sigmoid dose-response relationships.

References

Pinheiro, J. C., Bretz, F. and Branson, M. (2006). Analysis of dose-response studies - modeling approaches, in N. Ting (ed.). Dose Finding in Drug Development, Springer, New York, pp. 146--171

See Also

betaMod, logistic, sigEmax, linlog, linear, quadratic, exponential

Examples

## some example shapes
logistModList <- list(logistic = rbind(c(0.5,0.05), c(0.5,0.15), c(0.2,0.05), c(0.2,0.15)))
plotModels(logistModList, c(0,1), base = 0, maxEff = 1)