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.
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.
Usage
bartlettTests(y, ...)
# S3 method for default
bartlettTests(y, group, ...)
# S3 method for formula
bartlettTests(y, data, ...)
# S3 method for lm
bartlettTests(y, ...)
Value
An object of classes "anova" and "data.frame", with one observation
for each response variable in y.
Arguments
y
A data frame or matrix of numeric response variables for the default method,
or a model formula for a multivariate linear model, or the multivariate linear model itself.
In the case of a formula or model, the variables on the right-hand-side of the model must all
be factors and must be completely crossed.