LWestimate {LW1949} | R Documentation |
Generate Litchfield and Wilcoxon Estimates
Description
Generate Litchfield and Wilcoxon's (1949) estimates in the evaluation of dose-effect experiments.
Usage
LWestimate(estParams, DEdata)
Arguments
estParams |
A numeric vector of length 2, the estimated parameters (intercept and
slope) of a straight line on the log10-probit scale, typically output
from |
DEdata |
A data frame of dose-effect data (typically, the output from
|
Details
The input data are expected to be summarized by dose. If duplicate doses are provided, an error will be thrown.
Value
A list of length three:
-
chi
= the chi-squared statistic with associated P value and degrees of freedom, -
params
= the estimated intercept and slope of the dose-response curve on the log10 probit scale, -
LWest
= the Litchfield Wilcoxon estimates of ED50 with 95% confidence intervals and the number of records with partial effects (npartfx) as well as other metrics used in their step-by-step approach (ED16, ED84, S with 95% confidence intervals, N', and fED50).
References
Litchfield, JT Jr. and F Wilcoxon. 1949. A simplified method of evaluating dose-effect experiments. Journal of Pharmacology and Experimental Therapeutics 96(2):99-113. [link].
Examples
dose <- c(0.0625, 0.125, 0.25, 0.5, 1)
ntested <- rep(8, 5)
nalive <- c(1, 4, 4, 7, 8)
mydat <- dataprep(dose=dose, ntot=ntested, nfx=nalive)
mydat
intslope <- fitLWauto(mydat)
LWestimate(intslope, mydat)