R: Hartley's Maximum F-Ratio Test of Homogeneity of Variances

hartleyTest {PMCMRplus} | R Documentation

## Hartley's Maximum F-Ratio Test of Homogeneity of Variances

### Description

Performs Hartley's maximum F-ratio test of the null that variances in each of the groups (samples) are the same.

### Usage

    hartleyTest(x, ...)

    ## Default S3 method:
    hartleyTest(x, g, ...)

    ## S3 method for class 'formula'
    hartleyTest(formula, data, subset, na.action, ...)

### Arguments

`x` | a numeric vector of data values, or a list of numeric data vectors.
`...` | further arguments to be passed to or from methods.
`g` | a vector or factor object giving the group for the corresponding elements of `"x"`. Ignored with a warning if `"x"` is a list.
`formula` | a formula of the form `response ~ group` where `response` gives the data values and `group` a vector or factor of the corresponding groups.
`data` | an optional matrix or data frame (or similar: see `model.frame`) containing the variables in the formula `formula`. By default the variables are taken from `environment(formula)`.
`subset` | an optional vector specifying a subset of observations to be used.
`na.action` | a function which indicates what should happen when the data contain `NA`s. Defaults to `getOption("na.action")`.

### Details

If `x` is a list, its elements are taken as the samples to be compared for homogeneity of variances. In this case, the elements must all be numeric data vectors, `g` is ignored, and one can simply use `hartleyTest(x)` to perform the test. If the samples are not yet contained in a list, use `hartleyTest(list(x, ...))`.

Otherwise, `x` must be a numeric data vector, and `g` must be a vector or factor object of the same length as `x` giving the group for the corresponding elements of `x`.

Hartley's parametric test requires normality and a nearly balanced design. The p-value of the test is calculated with the function `pmaxFratio` of the package SuppDists.

### Value

A list with class `"htest"` containing the following components:

method

  a character string indicating what type of test was performed.

data.name

  a character string giving the name(s) of the data.

statistic

  the estimated quantile of the test statistic.

p.value

  the p-value for the test.

parameter

  the parameters of the test statistic, if any.

alternative

  a character string describing the alternative hypothesis.

estimates

  the estimates, if any.

null.value

  the estimate under the null hypothesis, if any.

### References

Hartley, H.O. (1950) The maximum F-ratio as a short cut test for heterogeneity of variance, Biometrika 37, 308–312.

### See Also

`bartlett.test`, `pmaxFratio`

### Examples

    hartleyTest(count ~ spray, data = InsectSprays)

[Package PMCMRplus version 1.9.0 Index]