drda (version 2.0.5)

effective_dose: Effective dose

Description

Estimate effective doses, that is the x values for which f(x) = y.

Usage

effective_dose(object, y, type, level)

Value

Numeric matrix with the effective doses and the corresponding confidence intervals. Each row is associated with each value of y.

Arguments

object

fit object as returned by drda.

y

numeric vector with response levels (default 0.5).

type

character string with either "relative" (default) or "absolute".

level

level of confidence intervals (default 0.95).

Details

Given a fitted model f(x; theta) we seek the values x at which the function is equal to the specified response values.

If responses are given on a relative scale (type = "relative"), then y is expected to range in the interval (0, 1).

If responses are given on an absolute scale (type = "absolute"), then y is free to vary on the whole real line. Note, however, that the solution does not exist when y is not in the image of the function.

Examples

drda_fit <- drda(response ~ log_dose, data = voropm2)
effective_dose(drda_fit)

# relative values are given on the (0, 1) range
effective_dose(drda_fit, y = c(0.2, 0.8))

# explicitly say when we are using actual response values
effective_dose(drda_fit, y = c(0.2, 0.8), type = "absolute")

# use a different confidence level
effective_dose(drda_fit, y = 0.6, level = 0.8)