calplot {chemCal}R Documentation

Plot calibration graphs from univariate linear models

Description

Produce graphics of calibration data, the fitted model as well as confidence, and, for unweighted regression, prediction bands.

Usage

  calplot(object, xlim = c("auto", "auto"), ylim = c("auto", "auto"),
    xlab = "Concentration", ylab = "Response", alpha=0.05, varfunc = NULL)

Arguments

object A univariate model object of class lm or rlm with model formula y ~ x or y ~ x - 1.
xlim The limits of the plot on the x axis.
ylim The limits of the plot on the y axis.
xlab The label of the x axis.
ylab The label of the y axis.
alpha The error tolerance level for the confidence and prediction bands.
varfunc The variance function for generating the weights in the model. Currently, this argument is ignored (see note below).

Value

A plot of the calibration data, of your fitted model as well as lines showing the confidence limits. Prediction limits are only shown for models from unweighted regression.

Note

Prediction bands for models from weighted linear regression require weights for the data, for which responses should be predicted. Prediction intervals using weights e.g. from a variance function are currently not supported by the internally used function predict.lm, therefore, calplot does not draw prediction bands for such models.

Author(s)

Johannes Ranke jranke@uni-bremen.de http://www.uft.uni-bremen.de/chemie/ranke

Examples

data(massart97ex3)
m <- lm(y ~ x, data = massart97ex3)
calplot(m)

[Package chemCal version 0.1-26 Index]