metRology (version 0.9-16.1)

plot.mandel.kh: Classical plots of Mandel's statistics.

Description

plot.mandel.kh produces classic plots of Mandel's statistics, suitably grouped and with appropriate indicator lines for unusual values.

Usage

## S3 method for class 'mandel.kh':
plot(x, probs = c(0.95, 0.99), main, xlab = attr(x, "grouped.by"), 
		ylab = attr(x, "mandel.type"), ylim = NULL, las = 1, 
		axes = TRUE, cex.axis = 1, frame.plot = axes, 
		lwd = 1, lty = 1, col = par("col"), 
		col.ind = 1, lty.ind = c(2, 1), lwd.ind = 1, 
		separators = TRUE, col.sep = "lightgrey", lwd.sep = 1, lty.sep = 1, 
		zero.line = TRUE, lwd.zero = 1, col.zero = 1, lty.zero = 1, 
		p.adjust = "none", ...)

Arguments

x

An object of class 'mandel.kh'

probs

Indicator lines are drawn for these probabilities. Note that probs is interpreted as specifying two-tailed probabilities for Mandel's h and one-sided (upper tail) probabilities for Mandel's k.

main

a main title for the plot. If missing, the default is paste(deparse(substitute(x)), "- Mandel's", attr(x, "mandel.type"), if(attr(x, "mandel.method") == "robust") "(Robust variant)")

xlab

a label for the x axis; defaults to the grouped.by attribute for x.

ylab

a label for the x axis; defaults to the mandel.type attribute for x.

ylim

the y limits of the plot. For Mandel's k, the default lower limit is zero.

las

the style of the axis labels; see par for details.

axes

a logical value indicating whether axes should be drawn on the plot.

cex.axis

The magnification to be used for axis annotation relative to the current setting of 'cex'.

frame.plot

Logical; If TRUE a box is drawn around the plot.

lwd, lty, col

Graphical parameters used for the plotted vertical lines corresponding to each value of Mandel's statistics (the plot is of type "h"). All are recycled across the prinmary grouping factor, allowing different measurands/test items to be identified

col.ind, lty.ind, lwd.ind

Graphical parameters used for the indicator lines, recyckled to length(probs). For attr(x, "mandel.type")=="h" the graphical parameters are applied to negative as well as positive indicator lines, applied outwards from zero.

separators

Logical; if TRUE, separator lines are drawn between groups of values.

col.sep, lwd.sep, lty.sep

Graphical parameters used for the separator lines.

zero.line

logical; if TRUE a horizontal line is drawn at zero.

lwd.zero, col.zero, lty.zero

Graphical parameters used for the zero line.

p.adjust

Correction method for probabilities. If not "none", passed to p.adjust prior to calculating indicator lines. Usually, indicator lines are drawn without correction (that is, with p.adjust="none"); specifying a p-

...

Other (usually graphical) parameters passed to plot.

Value

• plot.mandel.kh returns a numeric vector of mid-points of the groups along the x-axis.

Details

Mandel's statistics are traditionally plotted for inter-laboratory study data, grouped by laboratory, to give a rapid graphical view of laboratory bias and relative precision. The traditional plot is a plot of type "h", that is, simple vertical lines from the x-axis. For classical Mandel statistics, indicator lines are drawn based on qmandelh or qmandelk as appropriate. For robust variants, indicator lines use qnorm for the $h$ statistic and qf(probs, n, Inf) for the $k$ statistic. Note that this corresponds to taking the robust estimates of location and scale as true values, so will be somewhat anticonservative. plot.mandel.kh uses gplot for the main plot.

References

Accuracy (trueness and precision) of measurement methods and results -- Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. ISO, Geneva (1994).

See Also

mandel.h, mandel.k, mandel.kh, pmandelh, pmandelk for probabilities, quantiles etc. See barplot.mandel.kh for an alternative plotting method. gplot for the underlying plotting function.

Examples

data(RMstudy)

   h <- with(RMstudy, mandel.h(RMstudy[2:9], g=Lab))
   plot(h, las=2) # Lab 4 shows consistent low bias; 
                  # Lab 23 several extreme values.

   #Use colours to identify particular measurands:
   plot(h, las=2, col=1:8)
   legend("bottomleft", legend=names(h), col=1:8, lty=1, cex=0.7, bg="white")
   
   #Example of Mandel's k:
   k <- with(RMstudy, mandel.k(RMstudy[2:9], g=Lab))
   plot(k, las=2) # Lab 8 looks unusually variable; 
                  # Lab 14 unusually precise