From e83723b497d97cfb4e9e3a9803e06c81e7f0b12a Mon Sep 17 00:00:00 2001 From: ranke Date: Thu, 24 Apr 2014 16:03:41 +0000 Subject: - Added ChangeLog - Bugfix for lod() for the case of small x values (see ChangeLog) - Version 0.1-32 as just submitted to CRAN - Got rid of trunk directory, as I will not find the time to finish what I started there and it may confuse visitors of viewcvs in kriemhild git-svn-id: http://kriemhild.uft.uni-bremen.de/svn/chemCal@31 5fad18fb-23f0-0310-ab10-e59a3bee62b4 --- trunk/chemCal/man/lod.Rd | 83 ------------------------------------------------ 1 file changed, 83 deletions(-) delete mode 100644 trunk/chemCal/man/lod.Rd (limited to 'trunk/chemCal/man/lod.Rd') diff --git a/trunk/chemCal/man/lod.Rd b/trunk/chemCal/man/lod.Rd deleted file mode 100644 index e468e1d..0000000 --- a/trunk/chemCal/man/lod.Rd +++ /dev/null @@ -1,83 +0,0 @@ -\name{lod} -\alias{lod} -\alias{lod.lm} -\alias{lod.rlm} -\alias{lod.default} -\title{Estimate a limit of detection (LOD)} -\usage{ - lod(object, \dots, alpha = 0.05, beta = 0.05, method = "default") -} -\arguments{ - \item{object}{ - A univariate model object of class \code{\link{lm}} or - \code{\link[MASS:rlm]{rlm}} - with model formula \code{y ~ x} or \code{y ~ x - 1}, - optionally from a weighted regression. - } - \item{\dots}{ - Placeholder for further arguments that might be needed by - future implementations. - } - \item{alpha}{ - The error tolerance for the decision limit (critical value). - } - \item{beta}{ - The error tolerance beta for the detection limit. - } - \item{method}{ - The default method uses a prediction interval at the LOD - for the estimation of the LOD, which obviously requires - iteration. This is described for example in Massart, p. 432 ff. - The \dQuote{din} method uses the prediction interval at - x = 0 as an approximation. - } -} -\value{ - A list containig the corresponding x and y values of the estimated limit of - detection of a model used for calibration. -} -\description{ - The decision limit (German: Nachweisgrenze) is defined as the signal or - analyte concentration that is significantly different from the blank signal - with a first order error alpha (one-sided significance test). - The detection limit, or more precise, the minimum detectable value - (German: Erfassungsgrenze), is then defined as the signal or analyte - concentration where the probability that the signal is not detected although - the analyte is present (type II or false negative error), is beta (also a - one-sided significance test). -} -\note{ - - The default values for alpha and beta are the ones recommended by IUPAC. - - The estimation of the LOD in terms of the analyte amount/concentration - xD from the LOD in the signal domain SD is done by simply inverting the - calibration function (i.e. assuming a known calibration function). - - The calculation of a LOD from weighted calibration models requires - a weights argument for the internally used \code{\link{predict.lm}} - function, which is currently not supported in R. -} -\references{ - Massart, L.M, Vandenginste, B.G.M., Buydens, L.M.C., De Jong, S., Lewi, P.J., - Smeyers-Verbeke, J. (1997) Handbook of Chemometrics and Qualimetrics: Part A, - Chapter 13.7.8 - - J. Inczedy, T. Lengyel, and A.M. Ure (2002) International Union of Pure and - Applied Chemistry Compendium of Analytical Nomenclature: Definitive Rules. - Web edition. - - Currie, L. A. (1997) Nomenclature in evaluation of analytical methods including - detection and quantification capabilities (IUPAC Recommendations 1995). - Analytica Chimica Acta 391, 105 - 126. -} -\examples{ -data(din32645) -m <- lm(y ~ x, data = din32645) -lod(m) - -# The critical value (decision limit, German Nachweisgrenze) can be obtained -# by using beta = 0.5: -lod(m, alpha = 0.01, beta = 0.5) -} -\seealso{ - Examples for \code{\link{din32645}} -} -\keyword{manip} -- cgit v1.2.1