Bartlett Tests of Homogeneity of Variances
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.
bartlettTests(y, group, ...)
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 |
... |
other arguments, passed to |
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.
An object of classes "anova" and "data.frame", with one observation for each
response variable in y.
Michael Friendly
Bartlett, M. S. (1937). Properties of sufficiency and statistical tests. Proceedings of the Royal Society of London Series A, 160, 268-282.
boxM for Box's M test for all responses.
bartlettTests(iris[,1:4], iris$Species) data(Skulls, package="heplots") bartlettTests(Skulls[,-1], Skulls$epoch)
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