extRemes (version 2.2)

shiftplot: Shift Plot Between Two Sets of Data

Description

A shift plot is a plot of the quantiles of a data set y minus those of another data set x against those of x. Includes 95 percent simultaneous confidence bands.

Usage

shiftplot(x, y, pch = 20, xlab = "x Quantiles", ylab = "y Quantiles", main = NULL, ...)

Value

No value is returned, but a plot is created.

Arguments

x

numeric vector of length m.

y

numeric vector of length n.

pch

Plotting character.

xlab

Character string giving abscissa axis label.

ylab

Character string giving ordinate axis label.

main

Character string giving plot title.

...

Other optional arguments to plot function.

Author

Peter Guttorp

Details

The shift plot is a graph of y_q - x_q vs. x_q, where y_q and x_q denote the quantiles of x and y, resp. 95 percent simultaneous confidence bands are calculated per Doksum and Sievers (1976). The primary usage of this plot is where x is a control group and y is an experimental method; or something similar. For example, x might represent observations, and y might represent climate model output; or some such.

References

Doksum, K. A. and Sievers, G. L. (1976) Plotting with confidence: graphical comparisons of two populations. Biometrika, 63, (3), 421--434.

See Also

qqplot, qqnorm, approxfun

Examples

z <- rnorm( 100)
y <- rexp(30)
shiftplot( z, y)

data( ftcanmax)
shiftplot( y, ftcanmax[,"Prec"])