imam.Var.test {PairedData}R Documentation

Imam test of scale for paired samples

Description

Robust test of scale for paired samples based on absolute deviations from the trimmed means (or medians), called Imam test in Wilcox (1989).

Usage

imam.Var.test(x, ...)

## Default S3 method:
imam.Var.test(x, y = NULL,
       alternative = c("two.sided", "less", "greater"),
       mu = 0,conf.level = 0.95,location=c("trim","median"),
tr=0.1,  ...)


## S3 method for class 'paired'
imam.Var.test(x, ...)

Arguments

x

first sample or object of class paired.

y

second sample.

alternative

alternative hypothesis.

mu

the location parameter mu.

conf.level

confidence level.

location

location parameter for centering: trimmed mean or median.

tr

percentage of trimming.

...

further arguments to be passed to or from methods.

Details

The data are transformed as deviations from the trimmed mean: X=abs(x-mean(x,tr=0.1)) and Y=(y-mean(y,tr=0.1)). A paired t test is then carried out on the (global) ranks of X and Y.

Value

A list with class "htest" containing the components of a paired t test.

Author(s)

Stephane CHAMPELY

References

See Also

Var.test, grambsch.Var.test

Examples

z<-rnorm(20)
x<-rnorm(20)+z
y<-(rnorm(20)+z)*2
imam.Var.test(x,y)

# some variations
imam.Var.test(x,y,tr=0.2)
imam.Var.test(x,y,location="median")

data(anscombe2)
p<-with(anscombe2,paired(X1,Y1))
imam.Var.test(p)

[Package PairedData version 1.1.1 Index]