# bartlettTests: Bartlett Tests of Homogeneity of Variances

## Description

This function extends `bartlett.test`

to a multivariate
response setting. It performs the Bartlett test of homogeneity of
variances for each of a set of response variables, and prints a
compact summary.

## Usage

bartlettTests(y, group, ...)

## Arguments

y

A data frame or matrix of numeric response variables in a
multivariate linear model.

group

a vector or factor object giving the group for the corresponding elements of the rows of `y`

## Value

An object of classes "anova" and "data.frame", with one observation for each
response variable in `y`

.

## Details

Bartlett's test is the univariate version of Box's M test for equality of
covariance matrices. This function provides a univariate follow-up test
to Box's M test to give one simple assessment of which response variables
contribute to significant differences in variances among groups.

## References

Bartlett, M. S. (1937). Properties of sufficiency and statistical tests.
*Proceedings of the Royal Society of London Series A*, **160**, 268-282.

## See Also

`boxM`

for Box's M test for all responses.

## Examples

# NOT RUN {
bartlettTests(iris[,1:4], iris$Species)
data(Skulls, package="heplots")
bartlettTests(Skulls[,-1], Skulls$epoch)
# }