estimable {LW1949}

Determine if a Dose-Effect Relation is Estimable

Description

Determine if a dose-effect relation is estimable based on available data.

Usage

estimable(DEdata)

Arguments

DEdata

A data frame of dose-effect data (typically, the output from dataprep) containing at least two variables: dose, a numeric vector of chemical concentrations, and pfx, a numeric vector of proportional effects at each dose (see Details).

Details

A dose-effect relation is defined to be estimable if and only if there are at least two test records and there is some (non-zero) variability in both the doses and the proportional effects. The input data are expected to be summarized by dose. If duplicate doses are provided, an error will be thrown.

Value

A logical scalar indicating if a dose-effect relation is estimable.

Examples

conc <- c(0.0625, 0.125, 0.25, 0.5, 1)
numtested <- rep(8, 5)
nalive <- c(1, 4, 4, 7, 8)
mydat <- dataprep(dose=conc, ntot=numtested, nfx=nalive)
estimable(mydat)
nalive2 <- rep(4, 5)
mydat2 <- dataprep(dose=conc, ntot=numtested, nfx=nalive2)
estimable(mydat2)