UsingR: QQplot – R documentation

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QQplot

Creates a qqplot with shaded density estimate

Description

Creates a qqplot of two variables along with graphs of their densities, shaded so that the corresponding percentiles are clearly matched up.

Usage

QQplot(x, y, n = 20, xsf = 4, ysf = 4, main = "qqplot", xlab = deparse(substitute(x)),
        ylab = deparse(substitute(y)), pch = 16, pcol = "black", shade = "gray", ...)

Arguments

`x`	The x variable
`y`	The y variable
`n`	number of points to plot in qqplot.
`xsf`	scale factor to adjust size of x density graph
`ysf`	scale factor to adjust size of y density graph
`main`	title
`xlab`	label for x axis
`ylab`	label for y axis
`pch`	plot character for points in qqplot
`pcol`	color of plot character
`shade`	shading color
`...`	extra arguments passed to `plot.window`

Details

Shows density estimates for the two samples in a qqplot. Meant to make this useful plot more transparent to first-time users of quantile-quantile plots.

This function has some limitations: the scale factor may need to be adjusted; the code to shade only shaded trapezoids, and does not completely follow the density.

Value

Produces a graphic

Author(s)

John Verzani

Examples

x = rnorm(100)
y = rt(100, df=3)
QQplot(x,y)

UsingR

Data Sets, Etc. for the Text "Using R for Introductory Statistics", Second Edition

v2.0-6

GPL (>= 2)

Authors

John Verzani <verzani@math.csi.cuny.edu>

Initial release