Merge pull request #3 from TellAnAx/pull_requestHEADmain

add linearity tests for calibration data

1 files changed, 64 insertions, 0 deletions

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+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/linearity.R
+\name{linearity}
+\alias{linearity}
+\title{Assess the linearity of a calibration curve}
+\usage{
+linearity(x, y, method = c("slope", "curvature"), tolerance = 0.1)
+}
+\arguments{
+\item{x}{numeric vector of independent values (usually concentrations).}
+
+\item{y}{numeric vector of dependent values (usually the signal of the
+analytical device).}
+
+\item{method}{character string. Supported methods are "slope" and
+"curvature".}
+
+\item{tolerance}{numeric value between 0 and 1, describing the acceptable
+deviation from the median of the slopes or the signal-to-concentration
+ratio. The default tolerance is 10\%.}
+}
+\value{
+returns a diagnostic plot
+}
+\description{
+A function to create diagnostic plots for the assessment of the linearity of
+calibration data based on their point-to-point slope or the curvature.
+The underlying methods follow ISO 84 66-1:2021 and DIN 32 402-51:2017
+(German Industrial Norm).
+}
+\details{
+The point-to-point slope method is based on the assumption that the slope
+between two points should not vary greatly within the linear range.
+
+The curvature method is similar to the point-to-point slope method. Here,
+the ratio between the instrument signal and the concentration of the
+calibration standard is assumed not to vary greatly within the linear range.
+
+The use of the Mandel test is discouraged due to its limitations in the
+identification of non-linear behaviour of calibration curves (Andrade and
+Gomes-Carracedo, 2013).
+}
+\examples{
+# Continuous Flow Analysis (CFA) data
+data(din38402b1)
+
+# Point-to-point slope plot
+linearity(din38402b1$conc, din38402b1$ext, method = "slope")
+
+# Curvature plot
+linearity(din38402b1$conc, din38402b1$ext, method = "curvature")
+
+}
+\references{
+ISO 8466-1:2021. Water quality — Calibration and evaluation of
+analytical methods — Part 1: Linear calibration function
+
+J. M. Andrade and M. P. Gomez-Carracedo (2013) Notes on the use of
+Mandel's test to check for nonlinearity in laboratory calibrations.
+Analytical Methods 5(5), 1145 - 1149.
+}
+\author{
+Anıl Axel Tellbüscher
+}