R: Normal qq-plot with 95 Percent Simultaneous Confidence Bands

qqnorm {extRemes} | R Documentation

## Normal qq-plot with 95 Percent Simultaneous Confidence Bands

### Description

Calculates a normal qq-plot for a vector of data along with 95 percent simultaneous confidence bands.

### Usage

    qqnorm(y, pch = 20, xlab = "Standard Normal Quantiles", ylab = "Sample Quantiles",
        make.plot = TRUE, ...)

### Arguments

`y` | numeric vector of data.
`pch` | plot symbol to use.
`xlab` | Character string giving abscissa label.
`ylab` | Character string giving ordinate axis label.
`make.plot` | logical, should the plot be created (TRUE) or not (FALSE)?
`...` | optional arguments to the plot function.

### Details

Confidence intervals are calculated using +/- k, where

k = 0.895 / (sqrt(n) * (1- 0.01 / sqrt(n) + 0.85/n))

Gives a 95 percent asymptotic band based on the Kolmogorov-Smirnov statistic (Doksum and Sievers, 1976).

### Value

A data frame object is returned invisibly with components:

`x,y` | the data and standard normal quantiles, resp.
`lower,upper` | lower and upper 95 percent confidence bands.

### Author(s)

Peter Guttorp, peter “at” stat.washington.edu, modified by Eric Gilleland

### References

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

### See Also

`qnorm`, `qqplot`, `shiftplot`

### Examples

    z <- rexp(100)
    qqnorm( z)

    y <- rnorm( 100)
    qqnorm( y)
    obj <- qqnorm(y, make.plot=FALSE)
    str(obj)

    data( ftcanmax)
    qqnorm( ftcanmax[,"Prec"])

[Package extRemes version 2.0-8 Index]