QQplot function

Creates a qqplot with shaded density estimate

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

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.

Returns

Produces a graphic

Author(s)

John Verzani

See Also

qqplot, qqnorm

Examples

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