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@@ -1,3 +1,5 @@ +% Generated by roxygen2: do not edit by hand +% Please edit documentation in R/lod.R \name{lod} \alias{lod} \alias{lod.lm} @@ -5,83 +7,82 @@ \alias{lod.default} \title{Estimate a limit of detection (LOD)} \usage{ - lod(object, \dots, alpha = 0.05, beta = 0.05, method = "default", tol = "default") +lod( + object, + ..., + alpha = 0.05, + beta = 0.05, + method = "default", + tol = "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 \dQuote{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. - } - \item{tol}{ - When the \dQuote{default} method is used, the default tolerance - for the LOD on the x scale is the value of the smallest non-zero standard - divided by 1000. Can be set to a numeric value to override this. - } +\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 \dQuote{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.} + +\item{tol}{When the \dQuote{default} method is used, the default tolerance +for the LOD on the x scale is the value of the smallest non-zero standard +divided by 1000. Can be set to a numeric value to override this.} } \value{ - A list containig the corresponding x and y values of the estimated limit of - detection of a model used for calibration. +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). +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. +* 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. } \examples{ + 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) + +} +\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. } \seealso{ - Examples for \code{\link{din32645}} +Examples for \code{\link{din32645}} } -\keyword{manip} |