leveneTests | R Documentation |
This function extends leveneTest
to a multivariate
response setting. It performs the Levene test of homogeneity of variances
for each of a set of response variables, and prints a compact summary.
leveneTests(y, ...)
## Default S3 method:
leveneTests(y, group, center = median, ...)
## S3 method for class 'formula'
leveneTests(y, data, ...)
## S3 method for class 'lm'
leveneTests(y, ...)
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. |
... |
arguments to be passed down to |
group |
a vector or factor object giving the group for the
corresponding elements of the rows of |
center |
The name of a function to compute the center of each group;
|
data |
the data set, for the |
An object of classes "anova" and "data.frame", with one observation
for each response variable in y
.
Michael Friendly
Levene, H. (1960). Robust Tests for Equality of Variances. In Olkin, I. et al. (Eds.), Contributions to Probability and Statistics: Essays in Honor of Harold Hotelling, Stanford University Press, 278-292.
Brown, M. B. & Forsythe, A. B. (1974). Robust Tests For Equality Of Variances Journal of the American Statistical Association, 69, 364-367.
leveneTest
, bartlettTests
leveneTests(iris[,1:4], iris$Species)
# handle a 1-column response?
leveneTests(iris[,1, drop=FALSE], iris$Species)
data(Skulls, package="heplots")
leveneTests(Skulls[,-1], Skulls$epoch)
# formula method
leveneTests(cbind(mb, bh, bl, nh) ~ epoch, data=Skulls)
# use 10% trimmed means
leveneTests(cbind(mb, bh, bl, nh) ~ epoch, data=Skulls, trim = 0.1)
# mlm method
skulls.mod <- lm(cbind(mb, bh, bl, nh) ~ epoch, data=Skulls)
leveneTests(skulls.mod)
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