From 0b98c459c30a0629a728acf6b311de035c55fb64 Mon Sep 17 00:00:00 2001 From: Johannes Ranke Date: Wed, 18 Jul 2018 15:18:30 +0200 Subject: Correct references to the Rocke and Lorenzato model Rename 'sigma_rl' to 'sigma_twocomp' as the Rocke and Lorenzato model assumes lognormal distribution for large y. Rebuild static documentation. --- man/sigma_twocomp.Rd | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 man/sigma_twocomp.Rd (limited to 'man/sigma_twocomp.Rd') diff --git a/man/sigma_twocomp.Rd b/man/sigma_twocomp.Rd new file mode 100644 index 00000000..6f941093 --- /dev/null +++ b/man/sigma_twocomp.Rd @@ -0,0 +1,34 @@ +\name{sigma_twocomp} +\alias{sigma_twocomp} +\title{Two component error model} +\description{ + Function describing the standard deviation of the measurement error + in dependence of the measured value \eqn{y}: + + \deqn{\sigma = \sqrt{ \sigma_{low}^2 + y^2 * {rsd}_{high}^2}}{% + sigma = sqrt(sigma_low^2 + y^2 * rsd_high^2)} + + This is the error model used for example by Werner et al. (1978). The model + proposed by Rocke and Lorenzato (1995) can be written in this form as well, + but assumes approximate lognormal distribution of errors for high values of y. +} +\usage{ +sigma_twocomp(y, sigma_low, rsd_high) +} +\arguments{ + \item{y}{ The magnitude of the observed value } + \item{sigma_low}{ The asymptotic minimum of the standard deviation for low observed values } + \item{rsd_high}{ The coefficient describing the increase of the standard deviation with + the magnitude of the observed value } +} +\value{ + The standard deviation of the response variable. +} +\references{ + Werner, Mario, Brooks, Samuel H., and Knott, Lancaster B. (1978) + Additive, Multiplicative, and Mixed Analytical Errors. Clinical Chemistry + 24(11), 1895-1898. + + Rocke, David M. and Lorenzato, Stefan (1995) A two-component model for + measurement error in analytical chemistry. Technometrics 37(2), 176-184. +} -- cgit v1.2.1