fBasics (version 4021.93)

scaleTest: Two sample scale tests

Description

Tests if two series differ in their distributional scale parameter.

Usage

scaleTest(x, y, method = c("ansari", "mood"), 
    title = NULL, description = NULL)

Value

an object from class fHTEST

Arguments

x, y

numeric vectors of data values.

method

a character string naming which test should be applied.

title

an optional title string, if not specified the inputs data name is deparsed.

description

optional description string, or a vector of character strings.

Author

R-core team for hypothesis tests implemented from R's package ctest.

Details

The method="ansari" performs the Ansari--Bradley two--sample test for a difference in scale parameters. The test returns for any sizes of the series x and y the exact p value together with its asymptotic limit.

The method="mood", is another test which performs a two--sample test for a difference in scale parameters. The underlying model is that the two samples are drawn from f(x-l) and f((x-l)/s)/s, respectively, where l is a common location parameter and s is a scale parameter. The null hypothesis is s=1.

References

Conover, W. J. (1971); Practical nonparametric statistics, New York: John Wiley & Sons.

Lehmann E.L. (1986); Testing Statistical Hypotheses, John Wiley and Sons, New York.

Moore, D.S. (1986); Tests of the chi-squared type, In: D'Agostino, R.B. and Stephens, M.A., eds., Goodness-of-Fit Techniques, Marcel Dekker, New York.

Examples

set.seed(1234)
## rnorm - 
   # Generate Series:
   x = rnorm(50)
   y = rnorm(50)
   
## scaleTest -
   scaleTest(x, y, "ansari")
   scaleTest(x, y, "mood")